I've had to walk my coworkers through how at-will employment is effectively hiring/firing discrimination that one can easily hide. It's really difficult in at-will states to prove cases of discrimination outside of direct evidence of slurs being thrown around or written company policy. An employer can fire someone because they say they don't like the worker's personality, but in reality it's because the employer's a bigot. Employers don't have to admit they're racist or transphobic or anything, there's no mechanism to put pressure on employers outside of a union or calling in the (ugh) ACLU.

Workplaces just have to put up the equal opportunity employer thing in their hiring procedure and that's as effective as a shield they need.

Except my coworkers just said like, "Yeah, but if everyone figured out that the boss is a racist, no one will work for them." Yes, because nobody in America works for a racist.