If you set high standards and allowed only those who pass them to advance to the next grade, graduate HS etc. then you'd end up with clear racial disparities.
I don't want to get into a discussion about what's the cause of these disparities and who's fault they are. But, based on available data on e.g. SAT scores, we'd have Asian Americans doing the best, followed by whites, and with blacks at the bottom.
It'd provoke a flurry of media debate and negative attention on everyone involved. These people cannot fix the problem itself, at least not fully and certainly not quickly. But they can change standards to make it look like everyone is doing well. After all if you lower standards enough everyone will meet them.
It's a real problem and these incentives aren't going to change. Any solution will have to acknowledge and address them, not pretend that they don't exist and that incompetent or weak-minded politicians are to blame.
Meanwhile we're lowering standards and just passing every kid we can, for 'fairness'