People without savings, or who have dependents, might not have the ability to leave their jobs for the time that would be needed to retrain in alternative work. Or for that matter, bargain for better conditions.

Richer people with savings or parental support will always be able to quit & search for better work; and no doubt that’s where this arrogant ‘go and search for another job then’ sentiment comes from.

Note that China doesn’t have effective social security, so retraining isn’t an option.