Normally this isn't a problem as screening criteria like experience in language X is a bona fide job requirement, so even if such criterion filtered out minorities disproportionately, it's not a liability. Tacking on filters like 'must know programming language not used at this company' is going to be a huge stretch, and if your African American candidate pool is filtered out more regularly, that's a lawsuit waiting to happen.

So yes, crafting heuristics is hard, but manager's paychecks are larger for a reason.

That said, the African-American candidate pool in America is so vanishingly small that subtle tech bias at hiring time isn't the issue - the heuristics to filter them out started before they ever finished high school. (This has actually been a point of interest for me for a long time. I mentioned elsewhere a friend who has terrible spelling but a very successful career. He also happens to be black, which has been something else to overcome. We've talked for years about ways to encourage more black students to go into IT, which we both believe is a route to middle-class success with substantially less racial animosity than they'll face in other fields.)