I think the problem is that the word unionization encapsulates many different things which should not necessarily be tied together. Collective bargaining, employees having a voice on the running of the business, legal and advisory services provided by someone on your side as opposed to someone with interests diametrically opposed to yours (the CEOs, not the companies), elections of representatives, etc.

As a whole these (as the data conclusively proves) were better for workers and probably the companies as well at the expense of the C-level suits. But it is probably true that some of ideas implemented by unions did work against workers. The solution is not to throw the baby out with the bath water but to analyze and experiment with different union structures which reduce the negative effects and enhance the positive ones.

Unfortunately, Americans have decide to wholesale reject and vilify the only structure that empowers non-owners even slightly which despite all its faults was still better for most Americans, instead of trying to separate the effective ones from the ineffective ones, and are reaping the unequal society they have sowed.

Gotta give credit to our wealthy overlords who have done an impressive job of getting people to vote against their own interests by splitting people along various social dividing lines as well as magnifying limited failures of systems as endemic to them.