"Corporations gain bargaining power by (allegedly) shareholders pooling capital. It's very hard to find someone who'll argue that corporations shouldn't act in their own interests. Why is it therefore wrong for labor to do the same? It isn't, and it's way past time for workers to figure that out."
My father (a college professor not a union member) put it this way when I was in my late teens in the early 70s: If companies can have 10 people sit around a table and decide what to pay the worker, the worker should be able to have 10 people sit around a table and decide what they will work for.
Unions are a special interest group just like AARP, AAA, NRA, etc etc.