That's an excellent point! I can think of another example: In the movie "Hidden Figures" the black, female engineers at NASA are much better than their white, male counterparts simply because it was harder for them to get in. Perhaps the opposite is true today of engineering students at colleges with affirmative action?
Alumni preference is at least as big or bigger a factor in admissions than affirmative action. Many of the schools were segregated not so long ago, so you can guess how that affects the alumni pool.
This suggests that you think there is no perception bias that affirmative action is trying to counteract. You might be interested to know that when people try to correct for bias, they typically undercorrect.
Also, for people coming from more challenging circumstances, getting the same results is literally more impressive.
