Beam and SMA, you guys work at high end firms, looking for top devs, but your situation is rare. The vast majority work for mid tier companies like my former employer. They are underpaid, and annual increases are well under the rate of inflation. Many of them were technically excellent and hard-working, but many of them were doing PMO or analytical type work that I could train a reasonably intelligent person to do in a month. There was no way their skillset required hiring a visa holder to do that work.
At my company, there was no grand conspiracy. If I put out a req for a $60,000 salary manual testing position, I'd get citizens of average experience and ability applying, about what I'd expect for that salary back then. But the visa holders who applied would usually be vastly overqualified for the position. I never hired these people, as we didn't sponsor visas, but you can imagine over hundreds of thousands of positions how hiring managers would figure this out and let it drive salaries down.
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