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.