I have to admit it's somewhat amusing to see how surprised some people are to realize that people who aren't white can be racist too. Humans don't change much culture to culture once you get past a lot of the more superficial stuff.
Also, I dont think people really ignore people of color being racist within their countries. Most of the time when people bring up arguments stating that the people being racist are white people, its in the context of western countries with a colonial/slave trade past where systematic racism doesnt target white people.