I think people naturally tend to fear the unknown. Its just the way we are. It sucks if you have social phobia because that makes you a minority but to be a different race compared to your enviroment makes you a minority of a minority. Def an uphill battle.
Well yes and I think thats because of the culture difference between races. For example, when black people talk and white people talk there are clear differences in language and mannerisms. Some people are just more comfortable around their own races and will open up more around them which will allow for more communication.