One thing I'd like to see is competing unions. The UAW supplies labor to the big three US automakers, putting them in an unfair negotiating advantage; the UAW can easily bully them around. The UAW ultimately hurt themselves because it put the Big Three at a big competitive disadvantage. Some manufacturing left for right-to-work states, and some business left for (mostly) Japanese automakers.
I think that could help. Some unions at least, like the UAW shoot themselves in the foot. It’s very adversarial from both sides and often the worker in the middle is the one who loses out. Example the steel industry. They made labor so expensive the companies folded. Admittedly the industry ran aged inefficient systems that made their process uncompetitive. But the Union only cared about protecting itself. The companies only cared about immediate profits.
That's not at all what happened to the steel industry. 50% of all US steel production capacity has been built in the past 30 years and steel production has seen continuous and massive improvements in productivity. In 1920 it took 3 man-hours of labor to produce 1 ton of steel in the US, now 1 man-hour produces 300 tons. The contraction in steel employment during the 70s coincided with a recession and the development of the electric arc furnace. From 1974 to 1999, global steel industry employment fell by 1.5 Million people with large decreases both in developed countries and developing countries like Brazil and South Africa as employment per ton of production fell everywhere. The actions of one union in one country had nothing to do with it.
Old outdated technology (not sure about the stance the unions had back then on productivity improvements that would lower headcount) plus outsized pay demands for the given the productivity.
Old and outdated compared to what? Outsized pay demands compared to whom? Everyone around the world switched to the new technology at the same time. Employment per production fell everywhere simultaneously. This was not a case of labor becoming too expensive, it was a case of labor becoming unnecessary.