In my high school (a well-regarded, mixed-race high school in one of the worst-run districts in the US in the late 90s) the "advanced placement" courses were used as a form of segregation. White kids (drawn from an affluent enclave in the inner city and who made up 1/3 of the school) nearly all requested to be placed in "IB" classes instead of AP classes. It didn't matter if you were smart, because the material wasn't really any harder than the AP classes -- it was just what all the white kids did.

Black students (from a blue collar, middle class area; also 1/3 of the school) weren't excluded from the IB classes, but generally only the nerds/geeks requested placement. The kids who did were labeled "Oreos" by their peers, so there was peer pressure not to take the IB classes if you were from this area. These students generally came from good, supportive families, though their parents probably never went to college and thus had no real clue how to work the system to get your kid into college. Anyway, all the black kids were placed in "AP" classes instead of "IB" classes, just because that's how it worked.

The hispanic students (from a poor immigrant area, the other 1/3 of the school) were largely excluded from this system. They would be placed in "ESL" (English as a Second Language) or "remedial" classes, even though most were perfectly fluent in English (often they spoke Spanish at home) and the entire reason they were behind in a number of subjects was because the middle schools they went to were understaffed and under-resourced.

The racism was only super-obvious to the students because of the way they physically segregated the classes: each set of classes was in a different building. So you had the white building, the black building, and the hispanic building. People rarely had a reason to go to another building.

But the only difference between my high school and the bad schools in the district was that we had IB classes as an option, because we had a bunch of affluent white kids. Our IB classes were taught by great teachers who cared a lot, and I got a decent education. My teachers stressed the importance of going to college. But if you weren't an affluent white kid and you didn't know how to play the college game, you were no better off than if you went to another, worse high school.

And that's the difference, right there: if your parents went to college, they know how the game works. They know that University of Phoenix is not a real college, and they know what an Ivy League school is and why it's important. A kid who grows up with a father who is a welder and a mother who cleans houses doesn't have those resources. They know going to college is important, but they may not know the difference between a community college, a 4 year state university and an Ivy League. They may not know that you have to apply a year ahead of time.

It's not the affluent white kids' fault that they know this and their less affluent peers do not - you got thrown into this system as a confused 14 year old, so your parents were the ones making all the decisions when you started high school. But many white kids (and their parents) see attending a good university as their birthright -- if only they have the willpower to seize it. They see complex application processes as a challenge they have to rise and meet. There aren't even enough spots at these top schools for just a fraction of the affluent white kids, not to mention kids who don't even know that going to Harvard, Yale or Penn is a big deal.