It's because blacks are uncivilized and have low IQs.

The cast majority of them anyway.

So they know of no other way to express themselves or deal with things other than resorting to violence.

White people are the most intelligent and civilized people.

Therefore we're able to control ourselves much better, and don't have to use violence to express ourselves or solve problems.

Orientals are the most intelligent and civilized non-whites, and are generally able to control themselves much like white people, and not resort to violence.