^^^
It's for affirmative action purposes. Many businesses receive tax-breaks for meeting minority employement quotas.
Especially, umm, businesses that hire mostly minorities...*cough* *cough*
But hey I'm just a liberal right?
Anyways, about the standardized tests...I would assume it is because they have a lot of education researchers working to analyze trends among minorities.
For example, statistics about the educational habits of minorities would have to come from somewhere. I assume that they ask because it is valuable knowledge that can be studied.