I am an American, born and raised in the North-East. I'd say if anything, the people in my life are very cold and unemotional compared to the other states in my home country that I have not yet ventured to. If the OP wants a "totally real" experience, maybe you should give New York a try; I was born there and lived there for the first 11 years of my life. I'm weird since I always was and still am a pretty nice person overall, but New Yorkers are definitely a distant bunch who wants to hurry everything up and would give you a mean look if you ask them how are they doing, especially if you are a stranger to them. I've also lived in New Jersey and Pennsylvania. New Jersey is definitely fake nice, and can tip to dangerously hostile to social outcasts; Pennsylvanian folks are more direct in that, they take one good look at you at first, and immediately decide if they hate you or not. They'll even tell you this to your face.
I think the fake nice phenomenon is something that happens in the Southwestern states as well as the deep south. Never been to those places, but my dad has visited Texas once and the people there are super duper nice. Moreover, Americans in general are Christian Protestants and we were all taught to be respectful to others, though I'm sure some of us have taken it too far and it just comes across as awkward. I'd say it is even more awkward for me to greet someone casually and get a mouthful about being a phony. I'm sure even Holden Caulfield can take a greeting as just that: a non-threatening opener.
OP, it is truly not that deep. Nobody is trying to stab you in the back just because they want to know how you are doing. Not every conversation has to be 2deep4u in order for friendships to develop. Real relationships take time to flourish, and it often starts with a casual greeting and light moments here and there before everything deepens. It is, of course, a strange thing for me to learn as well, since I am a basket case by American standards, in that I really do love deep conversations with perfect strangers and find small talk to be particularly boring. But, I've learned that we have to start off small in order to create a life lasting relationship. Nothing wrong with that!