Earlier quoted context omitted.
It's harder for them to switch jobs, and depending on where they are in the process of applying for a green card, they may have to restart if they do switch. That kind of "loyalty" is easily worth 20k-30k for a lot of companies.
But they can always go home, there is nothing to stop that. So I would argue the loyalty they buy isn’t worth much.
Clearly you can see there is a difference between what a company needs to do to keep an H-1B employee from leaving the country, and what they need to do to keep a permanent resident employee from switching jobs?