Racism, sexism and politics play a far smaller role than you might imagine. It's a matter of skills, for example, in 2001 there were more than 16,000 Asian Americans who scored more than 700 on the math SAT. While there was less than 700 black Americans who scored more than 700 on the math SAT. So sure, in aggregate black males earn less than asian American males and white Americans (asian Americans also earn more on average than white Americans, are whites being discriminated against?), but if you compare apples to apples (similar education, experience, test scores, etc) then there is virtually no gap. The dogma is that statistical disparities demonstrate some form of discrimination, this assumes that there is an equality of performance which is virtually impossible to find in the real world.