This is actually a pretty nice system. It works like a protection for all workers, that their salaries are set by the union and it can’t be changed by the company.
Of course Tesla doesn’t like that, and of course capitalism in general hates that, because how are you going to replace then with cheaper workers? Or fire them when they feel like it (this is also regulated by the unions).
Capitalism is at its core about exploiting humans, and specially humans that are weak and not able to compete in the capitalism class system. It’s company profits over humanity.