My understanding of US history is that almost all meaningful worker protections were fought for and seized by labor unions. Things like the 40 hour work week, paid leave, overtime pay, etc.
What have they produced since 1940?
A bizarrely rightwing investment in the anti-Communist witch hunts, and a pretty enormous structural backlash in the form of the Taft-Hartley act?
Human minds being corruptible, applied to management and shareholders, does a good job of explaining why unions are necessary in the first place.