I agree that being locked to one employer is a kind of market distortion. Would you say non-compete clauses are too? I know they're not enforceable in California, but other states effectively lock local workers to their company because they're not allowed to move to another company in the same industry within a year or two of quitting.

Should we try to prevent companies from legally hiring local workers with non-compete clauses in their contracts? I think so. And I think it's a bigger issue than immigrants from the point of view of artificial wage distortion. Yet somehow these threads about immigrant workers get a lot more enthusiasm than threads about non-compete, so there's obviously something else to it. And I can't see what else besides the GP's "I'm an American".