That's just how some people are. It's how some people think. But perhaps if enough people take the effort to sit down and talk to others who think like that and change their minds through discussion then racism and all of that other bad stuff won't be as bad as it is now.
Because people are not perfect as they should be! It's as simple as that. Sad but true. In order to make this world a better place we have to change ourselves & believe me, that is not so easy as it seems.