Consider a toy admissions criteria where students go through the same process as today but students with black hair have to also win a game of rock paper scissors. There will surely be a large number of kids with black hair who are admitted and succeed. But the system would be plainly unfair and deserve to be fixed, despite many individual students with black hair being able to say "well I was admitted."
I was well-behaved and bright, but coarse I suppose.
I was too poor to participate in the fancy science trips, couldn't afford class materials, constantly late, and homework never got done due to what I remember as "family issues". I was bright and gifted, but a high achiever I was not.
I don't blame them for pushing me out of the system, I didn't play by the rules. But from what you're saying, that's part of the problem and I don't disagree... but allowing me to persist and annoy those gifted kids with resources, encouraging families, and ambition wasn't really fair now was it?
But forcing a child to use their non-dominant right hand could be considered a form of cruelty I suppose, so not seeing how they're really related.
When I go back home to Appalachia, I fall back into my old bad habits readily but if I got a call from my boss, I'm switching to "educated" and that's more than just ditching the drawl, it's modifying the entire way I structure my thoughts. I think that's very common and not unfair to expect from someone claiming that they desire education.
But to your point, I was not able to take algebra until 9th grade due to reasons that felt a bit discriminatory as you'd described, but my mother was a maniac and no one liked her, so hard to say if that didn't add weight.