https://www.theatlantic.com/business/archive/2017/02/the-dark-side-of-the-h-1b-program/516813/
“When technology firms hire foreign-born workers, they often pay them less than what they theoretically would have paid an American in that job. This leads to both lower pay for workers across the company and higher profits for the owners and investors. In other words, the H-1B program is a scheme to reduce wages and increase profits, which has been cleverly remarketed as a paean to multiculturalism and a win-win for American consumers and American inclusivity”.
Wage fixing is illegal under US law, but all these companies are doing it.