There is a mistrust, prejudice, bias, etc. about anyone not like us. As humans we categorize people and probably from some evolutionary survival instinct. Is this person going to help or hurt me? We also have a natural curiosity about other cultures. Sometimes the behaviors that come out of that are good, sometimes not so good.
We are also provincial in looking at things through our own sets of beliefs and needs. For example I'm guessing there are not too many No Border Fence bumper stickers up north, but they are everywhere here where the damn thing may be built. (And ironically, built by Mexicans)