Here is a wonderful video that shows some Sudanese people trying to assimilate into their new life in America. Their reaction to seeing Santa is wonderful.
I generally don’t feel like Americans are as rude or unfriendly as this video and the comments suggest. I think most of what you see here is common timidity that just comes out wrong. This shyness tends to be compounded when meeting strangers of another race. Midwesterners are notorious for keeping to themselves and being reserved. An old-school line of etiquette still exists here that basically says staring is rude and asking questions is meddling.
Thank God for kids, though. They’ll ask anything.
If you want to read a great book about a young man’s journey from Sudan to the U.S., pick up What is the What by Dave Eggers.