1: Every big tech interview I have been in the visa status is not even a question in the interview process. There is just a simple gate that “can you legally work in the US”? The hiring committee is not even thinking about visa (that’s a HR problem)
2: Are there confounders in that foreign workers are less likely to negotiate? Absolutely.
3: are there confounders in that people who come to US for study are likely already a self selected bunch who are striving to succeed? What are the typical grade distributions between foreign STEM students and US STEM students? Is grade a confounding variable? What happens if we control for GPA?
And finally does H1B abuse happen? Absolutely.
There is a lot of nuance that are not captured by surface level statistics. But nuance does not make outrage.
The American H1B system isn't about importing foreign workers that do a good job, it's about importing foreign workers that do a job no American could do. The system demands you look for some American do do the job first, and only if you fail to find one can you import one from overseas.
In that view, all the talk about GPA fall flat, because it doesn't matter if the foreign worker is better than an American worker, you are supposed to pick the American worker anyway.
The ‘mandatory interviews for Americans’ are just transparent scams.