They are constantly lobbying to increase the numbers of H1-B visas each year. It’s blatantly obvious that employers could find a US worker for almost all those jobs, they just want to pay less money and have a slave worker who cannot leave the job without having to leave the US. (If you come here with an H1-B, you can’t change jobs without losing that visa).
I’ve dealt with these sponsored indentured servants in the financial sector, and the wages themselves aren’t much lower than Americans. Where the employers really find value is making them work much longer hours/workweeks than they could ever expect from American workers; these people work longer days, and often six days per week.
The gains made by American workers over the last century are basically gone for most Americans today.