Some that help their parents, some that have kids, some that have sick spouses, some that brought their parents to live with them and support them due to health issues, some that have work visas.
I am simply saying that even though the right thing to do would be refusing, you also have to consider everyone's life circumstances when they make decisions.
The fact that they make $100k, $200k, $300k like another comment said means that they don't just need a job, they need a job making roughly the same amount of money and having the same benefits to be able to risk getting fired.
My original comment I wrote it so that we wouldn't just place everyone in the same group and generalize. It's not necessarily always as easy as refusing and risking your job. You're risking whoever else you support for example.