what a boring argument. Also wrong. I would put a lot of money on "you didn't a/b test collective bargaining with your own negotiation" because it's simply impossible, so you don't really know if that's true.
Also most workers are not in a job with a candidate shortage (and candidate shortages don't last forever, better have a union while you have the power to make it happen then when you become a throwaway widget for your company)
I've negotiated salaries that are 2 or 3 times what my peers have made in the same position.
I've also negotiated in non-standard vacation packages, like a fixed 2 months off every year.
That simply doesn't happen in collective bargaining.
I've hardly ever been a throwaway widget in any job and even when I was working shitty jobs I was the type to get promoted quickly. The only places this never happened were my 3 union jobs. And in each case I was forced to work for the union -- I wasn't seeking it.
When a union does not work or is corrupt, we fix the union, we don't give away the collective power to the opposing side of the negotiation: oh no, my lawyer is not doing my best interest he's only trying to rake up the fees! you know what? I'll let my opponent's lawyer represent me in court instead!
Also most workers are not in a job with a candidate shortage (and candidate shortages don't last forever, better have a union while you have the power to make it happen then when you become a throwaway widget for your company)