The stated question
Can an answer be off topic here?
Depending on what is meant by "off topic" the answer can go either way. If the intention is can answers be off topic in the same way as questions, deserving a CV as off-topic, the answer is "No." If the intention is can answers be off topic in the sense of not addressing the question, then the answer is, at least, "possibly." In the second case, using the "not an answer" flag would be appropriate. There is a major caveat involved in the "possibly" cases - does the answer meet the guidelines in the flag dialog box? Most important, relative to this question is the first sentence:
This was posted as an answer, but it does not attempt to answer the question.
If, in fact that is true for the answer in question, then that answer should be handled using the suggestions in the second sentence.
It should possibly be an edit, a comment, another question, or deleted altogether.
Each site has their own version of what qualifies as an "attempt to answer the question." I have not been able to follow it, but I do seem to recall that, either in chat or on Meta, that there has been some discussion about that issue already for our site. I wholeheartedly support the effort to define the accepted use of NAA flags for our site. From what I think I remember of the discussion, there were some points that didn't feel right to me, but I didn't have the spare time to engage in the discussion at that time, and only have a limited amount of time now as well. Still, it is a discussion that needs to be had and as a user of the site I should add my support, and my voice.
Part of my philosophy is to be as inclusive as practical. An internalized version of my thoughts can be expressed thus:
In seeking to be inclusive, we do not wish to open ourselves to the destruction of our site by those on self-serving power trips, or to philosophies and practices contradictory to our principles. In seeking to exclude those whose ways are contradictory to ours, we do not want to deny participation with us to any who are sincerely interested in our knowledge and assistance, regardless of race, color, sex, age, national or cultural origins, or sexual preference.
In line with that inclusiveness, I would apply the NAA flag to answers only if I am unable to see the connection between the question and the answer. If the answer offers a solution, not explicitly excluded by the OP, that seems to address the issue of the question, then I don't think it qualifies for the NAA flag. It might be a "stupid" answer, it might be nearly impossible for the OP to apply the answer to their situation, or it might be found to be "worthless" for any number of reasons. All such cases might earn a DV for the answer, but they still attempt to answer the question. I do consider extra-cultural answers to be explicitly excluded; a UK-based question needs UK-based answers, and a Chinese-based answer is, therefore, not an attempt to answer the question, and should be flagged NAA.
The hidden question
Now, on to the subtext, and what I think is the unasked question, the elephant in the room: What to do with answers that veer into legal realms when answering the question?
Unless it becomes site policy that, under rules-of-order for our site there will be no law-based answers on the grounds that invoking the law is, ipso facto, not "interpersonal" in nature, any question that has, or is completely, law-based, should be evaluated, on it's merits, as an answer, and a possible solution to the OP's question. Whether or not the answer includes any references to legal issues is immaterial to it's status as an attempt to answer the question.
To address the OP's listed questions:
Is it rude to use a driveway to turn around in the road? (Dismal showing, only one valid answer)
- None of the answers address the Australian perspective (The OP's stated location)
- Only two answers are from a UK perspective (explicitly asked for by the OP)
- All but the two UK-based answers are NAA on cultural mismatch grounds
- One of the two UK-based answers does not even mention the word "rude", and would also be flagged as NAA
- One answer would remain
Is it rude to drive at the speed limit on dangerous roads when another driver wants to go faster? (Much better showing. 15 valid answers, 9 of which even refrained from offering opinions about "what to do" in the OP's situation.)
- OP explicitly is "not asking for advice on what the best thing to do is"
- Three answers are not US-based and don't address the rudeness issue, flag NAA
- Another answer is invalid by OP's statement for giving advice and ignoring the question. Possible flag NAA
- Six do address the rudeness issue, and give advice, but seem to be US-based. (Acceptable)
- Nine answer the OP's question directly, and are, but for one, US-based. (Acceptable)
How to ask a vegan to stop telling me about veganism because I am not interested in it?
- A testament to our site's growth and development
- In my opinion, all ten answers are valid.
Ok, admittedly, there was much less said about the last one. I think each answer, in context of the question (each version thereof), is valid. Some may be more "workable" for the OP's situation, and temperament, yet all are "possible" solutions. The OP is free to try the one deemed most promising, in the OP's mind, not mine, and if it fails can try each of them until one does work. The one that works for the OP deserves the accepted mark, and other users are free to vote, up or down, as they see potential for each answer. This question is also one that will serve our site well by being potentially useful to many people later, without ever needing to ask a new variation of the same question. Congratulations to the OP for this one!
Still, the issue of legal issues in answers remains unaddressed. This is a site for people looking to improve their interpersonal communication skills, per the tour page. I am going to address only the aspects of two interpersonal skills: social acceptability and personal boundaries.
Social acceptability
In most cases the laws reflect the minimum accepted behavior of the society that created them. While "interpersonal" communication occurs between two people (or more sometimes), it also occurs within the greater context of society, and must conform to the laws of that society.
Discussions of the laws (speed limits, etc.) relative to what is or is not "rude" while driving does seem to be missing the point. I think a person can follow the laws and still be rude. Conversely, I think someone can violate the laws and still be polite. Both are socially unacceptable, on different grounds, showing that they are not, necessarily connected.
For that reason, the answers to either driving question which rely on legalities to determine "rudeness" are wrong, in my opinion. Nevertheless, they are still "answers" to the question, and do not deserve to be closed, or flagged NAA, solely on that basis.
Personal boundaries
Having personal boundaries, and enforcing them is part of being a mentally "healthy" person, and is essential for having healthy interpersonal communications, and relations. Two sites that discuss this concept are How to Create Healthy Boundaries from the University of Kentucky, and Healthy Personal Boundaries & How to Establish Them from the Essential Life Skills website.
Society has decided that some personal boundaries deserve legal protection. Different societies have protected diverse collections of such boundaries, to varying level, but they have protected some at least. Having a Pollyannaish outlook is nice, and probably makes for a generally happy life. Being a pessimist probably makes for an equally unpleasant life. I tend to give the benefit of the doubt while being a realist - fewer surprises and fewer disappointments. In any case, there will be situations where the maximum exercise of interpersonal communication skills at the highest level of effectiveness will still fail to resolve an issue. I'm not likely to be very successful trying to talk a carjacker from taking my vehicle, talking as much as I like, and trying to make him see the errors of his ways. If I have the legal right to do so, maybe I can "communicate" my preference to keep my car if I use a loaded .44! Even that is not a sure thing, however. Therefore, I think we, as a site, need to accept that some answers will have legal implications, and require recourse to lawful authorities. Other questions may benefit from legal input, even though it is not strictly required for an answer. Note that such answers must be valid in the OP's cultural context.
We, as essentially anonymous Internet users, are not lawyers, any more than we are mental health professionals. It has been, essentially, decided that the response to suicide type questions is to resort to saying, in essence, "seek professional help." Why then, in appropriate situations can we not say "seek legal help" to other users? If a question is presented where the OP claims that her husband pulls her hair and beats her regularly, for being 5 minutes late with dinner, or any of several other "infractions", what "interpersonal communication" skills should we suggest that she develop. What if a user claims that on Thursday nights the neighbor enters her home and won't take "no" for an answer? First, according to accepted usage on the site, we require that the OP supplies us with some cultural context. Now we know the former is in the UAE and the latter is in the USA. If we are not allowed to suggest legal avenues of redress, what's left to say? "Run?", "Hide?", "Pray?", "Move?", "Accept you lot in life?" Actually, for the former, there is not any legal recourse - the husband has that legal right! For the latter, there is legal recourse - tell her that it is rape, and to call 911!
Admittedly, both cases are contrived. It has been suggested to "deal with problems as they occur" and not to be worried about hypothetical cases that don't exist yet. A decent guideline, since most of us are not prognosticators with any significant fame. Reading the writing on the wall, and seeing the potential problems created by a knee-jerk decision, in response to an issue that has occurred is not the same as dealing with hypothetical cases. It is reasoned evaluation of the possible actions as part of selecting the (hopefully) best one for our site.
My answer to the hidden question is that including law-based information in an answer does not make it a bad answer. It, in fact, can be an extreme case of following the "back it up" policy. For it to be a "valid" answer, however, it absolutely must be laws that are from the same country/state as the OP. UK laws are worthless in Japan, and Minnesota laws are worthless in California. Obviously it would be improper to give binding legal opinions, no matter what the OP's issue is. Pointing to the laws that exist, stating how they are (likely) relevant to the OP's issue, and suggesting they contact a professional, should be acceptable. Of course, the answer is still subject to all other forms of evaluation for quality, etc. An answer cannot avoid a flag for NAA merely by referencing some law, any more that it should get flagged as NAA merely for suggesting legal approaches to the issue. If the post is an attempt to answer the question, and meets other guidelines, then it is a valid answer, and should be handled no differently than any other valid answer.
In defense of my answer to the vegan question, it does suggest non-legal efforts first:
I am going to formulate my answer under the presumption that you have already tried reasonable requests, and maybe even debates with them, and the results are the same. If you have not, then use those methods first - they can lead to a better work environment for you and them. If, however, such efforts do prove, or have proven, fruitless, then stronger measures exist.