Yup, an extremely abused program by them to underpay, and hold them hostage to the company. They could easily hire Americans, especially in the bay, but they chose not to.

Yes, in this case they know ahead of time. That is very true.

There are other situations where it may not be obvious unless you make it known.

Chaining people's immigration status to their employment just slavery with extra steps.*

*Yes, I know employees are paid however they can't change jobs and they are stuck with whatever pay the employer gives them.