I'm from the South and on a recent trip to California I noticed this. I smiled at people, opened doors and said hello and they all looked at me like an idiot.
I'm curious about the psychological aspect of it. Maybe they see it as a sign of weakness, for instance, to thank someone for the act of opening the door.
Or perhaps they view it as an attempt to extort by trying to "cause" them to say a thanks.
Or return a smile.
Seriously sick, twisted thinking.