You think people aren't racially discriminating when they hire people!? Seems to me they absolutely are, which is why I don't think "we can do" much about age discrimination either.
That isn't what the GP said. The GP pointed out that it is possible to do something about discrimination if we make a concerted effort. Racial discrimination has not been eliminated but has been significantly reduced.
Maybe I'm wrong. But if you ever come to Auckland, NZ I could show you a lot of suspicious coincidences.
And that's not "all you can do". Societal attitudes regarding race have shifted dramatically over the past few decades.
We also banned discriminating against older people in the 60s, so it's not clear where to go from here.