You know why?
I think a big part of it is because the guys who flew RC aircraft over the years have been serious hobbyists and not "I bought this on Amazon" goofballs.
I walk my 15 year old dog near a park where a lot of these guys fly their rigs. I've never met one who wasn't thoughtful about what he was doing and respectful of others' safety. They don't fly over the kid's playground, they don't fly over the traffic on the surrounding streets. They're human beings. A lot of them bring their kids and teach them the same appropriate behavior, while getting the kids interested in a cool hobby.