not just because they make lessHaving an indentured servant who must take all your arbitrary crap and smile, smile, smile while doing it is just tooooo much of a perk for the petty tyrant flavor of master.(because they don’t), but because they won’t argue with management and they will take abuse without complaint.
Although most managers are good decent people, one does not have to look too far in any job market to find a martinet.
They don’t make less. I know this because I work with them. We have laws that make that perfectly clear as far as h1b, and green cards in The IT industry and I expect laws are on the books for other industries that bring in folks from foreign countries.