Union wages are consistently higher than non-union wages, so we have evidence that unions are an improvement compared to direct relationships with employers.
Source: literally every long-term economic comparison of wages done for the last 50 years.
Activists always want to take credit, but it's the engineers and scientists who actually did the thing that changed the pattern that had lasted for 10,000 years. Unions are just one particular way of structuring one side of a human conflict that is as old as civilization and as inherent as gravity.
[1] https://en.wikipedia.org/wiki/Triangle_Shirtwaist_Factory_fi...
For thousands of years those bad conditions reigned. For thousands of years, 'organized labor' changed nothing. Then technology changed, and suddenly 'organized labor' became able to offer all these wonderful things. Does it sounds like 'organized labor' can take credit for all that? That they just happened to succeed in the decades after industrial technology took off?
The timeline clearly indicates technology, which increased productivity across the board, as the root cause.
If unions raised wages enough to offshore jobs those jobs would no longer exist, that union would not exist, and those wages would not contribute to the total average wage breakdowns that show an 18% increase in wages for union members.
Yet, today, union members make 18% more than non union members. The only thing the data actually suggests is that if you want an 18% raise you should join or start a union.