I just learned that, in the US, literally asking certain questions on a job interview (as opposed to making discriminatory decisions based on the answers to those questions) is illegal (as found here and here).
It turns out, however, that asking itself is not a punishable offense. Employer can get away with asking those questions until someone uses them as evidence of discrimination in a court case.
Such evidence, by its nature, is only circumstantial. That is, it does not directly show discrimination (after all, the interviewer could be simply doing small talk / assessing soft skills when asking "what is your gender identity?" — rather than having discriminatory intent in mind). But, in conjunction with other corroborating evidence (e.g. rejection despite apparent fitness to work, and acceptance of a less fit applicant who is of a different answer to those question) these questions could indeed prove discrimination.
Now, what standard of proof? "Balance of probabilities" (as for a tort), or "beyond reasonable doubt" (as for a crime)? Is such discrimination a crime in the US, or tort, or what?
Is it the case that those questions prove discrimination just because the statute says they do, despite that otherwise they would not (especially given that state of mind of the employer is not determinable)?