This is relevant because employment discrimination law in the USA prohibits the use of any tests where certain protected racial categories score worse than the national average by a specific amount. Usually that amount is specifically that each protected race must achieve four fifths of the passing scores of any other group. (Yes, that is a vague and easily gamed standard. It was made up by lawyers in the Department of Justice, not by game theorists in the DoJ.)
The result in, for example, fire and police departments has been that all the tests, especially written tests, have been dumbed down so that 80% of everyone passes. That is automatically considered to fulfil the four fifths standard. Then candidates are chosen by political patronage or random selection.
The result is much worse average qualifications. If there were just a racial quota like US universities use, you could pick the top X% of people from each protected underperforming racial category but also the top people from each of the high performing categories. In the Jewish Problem and four-fifths scenario, you don't get the top people from the high performing category except by chance and with four-fifths not from the protected categories either.
The new, state of the art federal civil service exam written under the Carter administration was abandoned because protected racial groups did badly. the obvious solution of race norming was considered out of bounds because Republicans could demagogue against the practice. The entire civil service exam system was dismantled instead and race based hiring is promoted with no objective standards. The result is the worst of all possible worlds. It's just lucky that federal jobs are still plush enough that good people work hard to game any system to get them.