I think it's trickier to gauge in knowledge work because there's a ramp-up period, even for top performers. Just understanding the institutional context that led to the current ecosystem - essentially understanding every Chesterton's Fence you encounter - takes a substantial amount of time.

They don’t have the money to hire lawyers to pursue discrimination suits, and the potential SME employers frequently don’t have the balance sheet to be collectible.

It’s a different ballgame when you can gamble $20k to make $1M.

Typically there's a lot of onboarding, and even a good candidate might not get a lot done in the first month or three... By the time you realize the new hire isn't a good fit, you've spent a ton of time on training.

Otoh, if you hire me to frame a house, it'll be objectively clear you need to get rid of me in the first hour, if not the first ten minutes. I don't know how I'd get past a screening for that either, but still.