No doubt this is because of the ever increasing cost of going to college in the USA. This favors kids with parents that can pay for some part it, and black and hispanic households tend to have less money than other etnic groups.
This won't fix the problems of certain groups being excluded though. We have free public schools in the U.S. and these are still some of the most segrarated insitutions, the overwhelming majority of children go to school where their ethnic group or race is the majority.
