I agree that SV (the actual physical location) and the US software industry are less racist than most of the rest of the US. But they're still way more racist than, say, Porto Alegre or Caracas, which are no egalitarian utopias either. And the reason for this is, in fact, the broader culture of the US. (Not “American culture” because that would affect Brazil and Venezuela just as much as the US.)

There are significant numbers of upper-middle-class black people in the US, and there have been for decades now. Their kids still don't end up as programmers in significant numbers. White rednecks' kids do; they're facing a pretty stiff uphill battle too, but a lot more of them prevail. That's racism, not just classism.