Crab mentality is quite widespread in USA for some reason. "If you don't like it quit". Why not "If we don't like it then lets band together and unionize and get better terms on our deal" ?
From an individual perspective, switching jobs is the simplest and most effective way to improve your situation, and will likely get you more money than a union could negotiate for.
From a group perspective, a culture where quitting is normalized generates similar benefits to unions. Employers will make concessions and raise salaries if they have too much trouble retaining good people.
Your comment "get you more money" makes it seem like you think more money is the primary reason people join a union.
People also join a union to have better defense against capricious management decisions ("Give the superintendent's kid an A or I'll give you bad teaching assignments".)
People are also willing to take a lower salary for better job security.
Grievances can be mediated through a union rep, like the shop steward, who is more likely to be aligned with the employee than the company's HR rep or management.
In some companies, unions have right to have a member be present at board meetings.
> where quitting is normalized generates similar benefits to unions
That's somewhat tautological. The power of unions is based on people quitting. The point is the quitting together is more effective than quitting piecemeal, such that even the risk of having mass coordinated quitting can be an effective tool for the union.
This is not possible if you're working in the kitchen or cleaning. Sucks for you, right? You must be in this situation because you've chosen it, you can just switch jobs otherwise.
In a world where you're only surrounded by tech workers your whole world might become tech with an occasional ring from the food delivery man the only contact with the outside world. I've never been in silicon valley but that's how I imagine it to be.