If it wasn't for unions, child labor would still be a thing. Have you ever worked in a factory or construction job ? Ever watch someone accidentally hit their hand with a nail gun and get a 2 1/2" corrugated staple embedded in their arm ?
I have. And I can tell you, without the union not only would he have been out of a job but lost his health insurance. The surgery costs were VERY high, it would have bankrupted him. He was also paid something like 85% of his salary when he was out of work for a few months.
Good unions provide workers with protections that most people never think of. Sure, there are a lot of terrible unions like the one for cashiers at a supermarket. The good unions provide protection and help in dangerous jobs.
Now, I am sure someone will say that assembling a computer has little to no risks. Which is very far from the truth. There are tons of chemicals, sharp objects, and heavy machines for things like machining the aluminum.