"But what if some of the best candidates aren't getting hired ..."

But what if they are and current racial composition just reflects that?

If there are talented minority coders who are overlooked by Google/Apple, it should be possible to exploit this market inefficiency, no need to enforce it.

But what if some of the best candidates aren't getting hired because companies overlooked them while trying to hire alongside racial quotas? Seems much more likely.

It's that for many jobs good enough is in fact good enough, and then the hiring question turns into a quality-of-life issue. Some people really don't like to sit across from blacks, queers or Trump voters.

Blind hiring tests can be done.

Oddly enough there is no drive for it.

Curious, that.

Because it's harder to do and people think they're better at judging candidates with more info than they actually are.

Not very curious, that.

I agree with the second proposition but don't see why it should be harder to accomplish. It appears to be largely a matter of requesting some information through a channel that does not permit nonessential observation, like a Turing Test or rather the original Victorian game, a reversed Imitation Game.