Thanks to many edits (and last great one from @avazula), this question about "courtesy" has been (temporarly) saved and could probably be reopened.
"Is it common to leave something in someone's house and expect them to think it's a gift for them?" is part of the "non-verbal communication" skill, and has a lot to teach to people who won't easily pick up the clues when it's not directly said or written.
It's a very good example of how hard it is to understand people's meanings. It leads to misunderstandings, can ruin relationships, and let some people puzzled. Thoughtful gestures, or small gesture having big impact, it seems important that people who have no knowledge/understanding about these can get some input.
If the question (or its answer) can still be improved, please share your opinions/ideas.
Update: thanks to who edited/improved/voted to reopen. Anyone with a better idea (yeah, I know, it's going to be an off-topic phrasing request ^^) about how we could make the title match the body and the ideas behind OP's concerns?