Thank you for this. I used to hear the term "wage theft" and associate it with underpaying workers relative to the value they produce, until I learned that wage theft refers to underpaying workers relative to what they're contractually entitled to.

Don't get me wrong, I do believe that it's a problem to pay workers far less than the value they give, but "you're not paying me what I'm worth" is not as egregious a problem as "you're not paying me what you agreed to pay me."

In most cases, underpayment can't be fixed by an individual for themselves without a wide scale strike (which many workers aren't in a good position to risk,) but wage theft is currently illegal and can be addressed by filing a complaint. So it's better to keep it clear what wage theft is so that the average worker doesn't dismiss it as some communist idea, at least until wage theft is no longer the greatest form of theft in the US.