Communication. Talk to your teammates, its usually pretty obvious if someone is bullshitting you.

Decent managers already know who their over- and under-performers are. Using "time at work" as a proxy for performance generally doesn't work well in general.

I know how performance is judged, functionally speaking. I am suggesting that the specific expectations that would be communicated in that context are straddling the boundaries of what is legal in some places.

Interesting, good point. I read your comment as suggesting a company with strict published policies around kids, benefits, work requirements, etc.

Didn't consider the case where individual conversations might run afoul of the law.

It is legal and normal to discriminate on the basis on how much work you do. I think you can even legally discriminate on whether someone is a parent - protected classes are Age, Race, National Origin, Religious Beliefs, Gender, Disability, Pregnancy and Veteran Status.

You are correct, under federal law, and for non-government jobs.

But, states and localities often add protected classes beyond federal requirements. As has the executive branch of the US government for federal jobs.