RSSIt’s the same as why the gender disparities in occupations in the Nordic countries are greater. There is less environmental pressure pushing women into occupations that earn more money, so they are freer to choose the occupations that they prefer, so their natural proclivities are more able to be expressed. With the environmental pressures that drive people to crime removed you are left only with the natural proclivity to crime. The disparity at the higher income level is closer to the disparity in the traits that lead to criminality.
Today, however, most Americans seem to think that racial discrimination is an intrinsic moral enormity – and see no reason to ask themselves why. Such is the effect of mass conditioning.
I think the answer is simple. Discrimination is seen as insulting to the discriminated against party. We feel guilty about implying that some group is undesirable to interact with. We know that we don’t think of it as a mere matter of different taste or mere idiosyncratic preference. By treating it as a serious moral infraction we give away what we really believe about the different races.