“But of course those who recoil from the idea of permitting race as an admissions factor generally have no issue with permitting the use of class”
I’m not convinced of that. I think people who believe in selection on the basis of intellectual merit would mostly agree that you need to adjust the achievement criteria to account for the fact that those with more resources (e.g. test prep or schools offering more APs) will generally have higher realized achievements (test scores etc). Oxbridge interviews try to do that and identify academic potential. They don’t do it perfectly, but US interviews don’t even have that objective (for a start they aren’t done by the people who would teach you).