I've always thought that if a union is good enough for LeBron James and Tom Brady and Mike Trout, it's good enough for anyone. The same reason professional athletes have a union and would not dream of doing without one still fully applies to everyone else.
I agree with you, but consider the "outplaying your contract" and bad blood via arbitration problem we see in more and more (American) sports. Tech jobs aren't like being a plumber, one can't exactly say you need X amount of hours to be ready to do something, even only in the eyes of the law.