In Econ 1A everyone has to memorize the definition of pure capitalism --a market where no one buyer and no one seller can affect the market price. This was the case of the labor market before we had factories. Back then we had as many households buying handywork as there were shops selling it. When factories were invented, suddenly the labor buyers (factory owners) were calling the shots. This stopped when the workers formed Unions and made the number of labor buyers equal to the number of labor sellers. The unions restored the pure capitalist market.
Things keep changing. Over the last few decades there's been a big shift to small non-union businesses. Now, unions are neither good nor bad; they're irrelevant --a thing of the past.
I pretty much agree yet these threads are full of "It's the unions' fault!"
I guess I miss the nuances.
Government unions are mostly lobbyists.