about 12 years ago I worked at a very large non-tech company that had outsourced to contractors to work on some code. They had a room in the basement for about 20 kids on H1B visas that were clearly right out of college. This was in a major city that had plenty of jr developers around, they just would expect more money.

I forget the contractors company name but they came up on HN at the time for being abusive towards their employees who risked deportation if they stood up for themselves. If I find specific examples I'll add them later, but you can probably just search hn for h1b.