It's fair enough to say that American auto unions (and very importantly, auto company management and ownership) would do well to model themselves after Germany's system. It's not a universal truth that all our unions are ineffective.
You could say that about many different things: if we just did it like the Germans, everything would be better, right? But how exactly do you actually do that? We're not Germany. You could go to Zimbabwe or El Salvador and tell them the same thing ("just be like the Germans or Japanese and you won't have all these social problems!"), but that isn't realistic; if it was that easy, every country would be copying the Germans and Japanese.
As for a universal truth, I haven't seen any evidence yet that unions in America actually work well. In Germany, yes, but this isn't Germany.
I could compare all companies to the worst examples too (e.g. all startups are Theranos) but that would never be taken seriously nor would it be fair yet somehow with unions that level of analysis is taken seriously.