Here in Australia, we're a fair bit more heavily unionised than you are over there, which helps keep some of the power imbalance in the employers favour in check.
Not that unionisation is perfect though either. When I was growing up it was a regular thing for unions to wield their collective power in aggressively overreaching ways - it was common for transport unions and fuel industry unions to have extended strikes over pay claims right before christmas, tand truck drivers would stop delivering to stores, oil refineries would shut down resulting in fuel rationing, and dock workers would stand down resulting in queues full of container ships full of imported goods on the horizon at the beach in summer.
The reaction to a bad job is... you quit and find another one.
Granted, there are substantial power balances between the parties, which is why even the US adds some federal protections (can't fire or decide not to hire for certain protected reasons, wage and work hour limitations) and states can add more (most relevant to HN, California's ignoring non-compete agreements).
But this particular example just smacks of entitlement, when the government worker protection departments should probably be spending more time on chicken processing factories running 18 hour shifts around band saws and paying minimum wage.
Which is also an option in non At-Will Employment states.
In most of the US, for most US jobs, absolutely nothing. The vast majority of US workers are at-will employees. Their boss can call them up at any point and say “We’ve decided that starting next pay period, we’ll be cutting your salary in half. Have a great day!” The employee’s options are to accept that or start job hunting.