What makes it "time theft", whatever that means?

US employers have worked very hard to make many of their workers "exempt" [1] such that they don't have to pay for overtime and can make people work egregious hours without getting in legal trouble.

If that's not "time theft", then I don't see why an exempt worker who can do the work of two people shouldn't get paid for doing the work of two people. It would be different if they were hourly workers and they were double-billing for the same hour, of course. But I don't think that's what's happening here.

[1] https://www.investopedia.com/terms/e/exempt-employee.asp