I’m not sure taking liberties with things you don’t own, is always the best policy, nor is putting the entire responsibility on the owner.
I don’t think this is something you can boil down to a simple black and white.
If you put a server on the public internet and I send it a message (assuming I’m not using ill-gotten credentials, etc.), anything it responds with is your problem, not mine.
No. It could be said, but wouldn't be true - objects in a domestic front yard are nothing like pamphlets placed on the sidewalk.
Not sure why you are acting so obtuse.