Unions are important. They give voice to people within companies who have tens of thousands to hundreds of thousands of employees. Most people are not adept at negotiating for anything. So, yes, conceptually, they are a good idea and they should not go away. I never proposed that they disappear.
The problem is that American unions succeeded at entering into a destructive feedback loop where union management had to justify their existence (and huge salaries) by always grabbing more and more for the membership. Even to the point of the ridiculous examples I laid out from the automotive industry.
This seems to be a common failure in both government and organizations such as unions: Past a certain point it is nearly impossible for management to go to their members and say something like "We need to stop asking for more on pensions, salaries and benefits because we are going to cause damage to the future viability of this company".
Why? Because of pandering or populism. There's always a sick would-be leader who will step in and counter that with gifts-a-plenty while vilifying the guy who proposed moderation or, the unthinkable, cut-backs and concessions in order to ensure things remain viable for the greater good.
That's the mechanism that has turned a lot of unions (not all) in to agents of destruction rather than responsible participants in an ecosystem. Union members are NOT bad people. They, like anyone else, would like to live better, earn more and retire well. They trust and follow the people they hire to represent them, the union leaders. This leadership, high on power and, yes, in cooperation with incompetent company executives ultimately fails their membership by creating situations where the company's own survival becomes mathematically impossible.
You know, what's interesting about this is that down-votes fail at masking reality. We have an entire city, if not a state, to serve as evidence for the sheer destruction caused by the combination of bad union leadership when combined with incompetent corporate management. Had these companies not been bailed out to the tune of billions of dollars Detroit would have cratered under the weight of an utterly unsustainable equation.