Great comment. It's really shocking how close to the legal line Silicon Valley tech companies get, and the extent to which many of them actually cross way over the line. A huge number of interviewers I've encountered are in extreme need of training so they don't so casually put their companies at legal risk. If I was Lawful Evil, I could probably make a career out of just suing companies for discriminatory hiring practices, due to the various landmines poorly trained interviewers routinely step into.

BigTech seems to be the best at it. They tend to have rigorous training, and often have a "safe question bank" that interviewers pull questions from, which are all vetted by lawyers and are known not to put the company at legal risk.