I think part of it is just sticking their heads in the sand. US public schools in general do terribly at actually teaching people to read or do math and no doubt for minorities it is even worse. If you just stop measuring you won't see how bad it is anymore.

On top of that it's gatekeeping, if public schools don't actually teach anything except ideology anymore, then the elites don't have to worry about pleb kids coming to compete with theirs.