> I'd imagine several things could be used as this proxy to varying degrees, everything from income to criminal history
But I think you could also make a compelling argument that many of those things are accurate proxies primarily due to the legacy of more overt discrimination, and it would be difficult to impossible to disentangle that.
Life is messy. I think there's a fine line, but still a difference, between factoring in past injustices and factoring in current negative conditions that resulted from past injustices. Throwing your hands up and saying "it's too hard" seems a bit of a cop out for the latter.