They and employers know that if they are fired or laid off, they 'get' to go back to whatever third world country they came from.
One co-worker was deported back to Iran the day after he was laid off.
He was an Iranian dissident, and after he was forcibly returned to Ayatollah Land, no one ever heard from him again.
A man or woman would put up with a LOT of abuse to avoid such a fate.
A goodly fraction of managers are more than willing to provide it.
That's why so many get hitched early and crank out a litter of anchor babies.