That's probably not a great example given that the rust belt was thick with unions.

And in general the US has a cost of living problem because the various levels of government keep getting captured by people who want regulations that make costs to go up because they're the ones getting the money. That makes US workers less competitive because of the corruption-induced regulatory costs, which is exactly the opposite of markets working as they should, except insofar as "industries move out of countries with high corruption and inefficient laws" is supposed to apply pressure to countries to get more efficient rules.

It's almost as if there is no silver bullet to these problems and we have to better than rely on dogma like "unions always good"