The problem is that they benefit workers not through productivity increases, but via collective bargaining, i.e. at the expense of society. Consider that when unions go on strike, they reduce economic productivity and disrupt the economy. Likewise, when unions fight to prevent factories from closing to protect the jobs of workers, this causes an inefficient allocation of resources - so now companies must bid up the prices of raw materials to produce things that nobody wants just to keep some people employed. Unions oppose automation for similar reasons, which is why we have the most inefficient ports in the world (worse than Africa!).
So in sum, unions do literally nothing to make society better off. What benefits unionized workers receive come at cost of society (including other unionized workers!)
>If you could come up with an equitable and non exploitative system that works for everyone, suddenly you no longer have a need for unions.
Capitalism is working great, actually. It would work better without unions.
"Economics" in the sense of "any sort of understanding of how the world works", not so much.
Drain the rot from your brain. Ew.