to say that if Michigan was to acquire back all of the jobs it lost would be the end of the auto industry is rather difficult to grasp.
Let me walk you through it.
If US companies had to manufacture their products in the US where wages are higher, their costs to produce would rise and so their prices would have to rise too.
If the wages of all of their customers also went up (what protectionist want) and the cost of all of their competitors products also went up, then this would work out fine. The two big problems here are 1. that US corporations sell to global markets, so not all customers would see increased wages, and 2. not all global companies manufacture in the US, so their products would not get more expensive.
Capitalism thrives on market competition, and in this scenario foreign made goods of equal quality become relatively cheaper, and so gain market share. US companies are stuck with a more expensive product that doesn't sell. The US companies can't compete, because they are wasting money on inefficient production.
Then you have to remember that the US is already an evolved economy full of middle class consumers, but the rest of the world has approximately 3 billion third world inhabitants on the cusp of middle class prosperity, who will become active consumers in the coming decades. That is where future profits will be generated, and US companies need to sell in those markets. Those new consumers will not choose overpriced US-made goods if there are equivalent but less expensive foreign-made goods made by the same US companies, or foreign competitors.
In order to be competitive in a growing global market, US companies need to keep their costs down to keep their goods affordable, and that means making them where labor is cheap. Cars and avocados are not different, in this respect.
So Detroit is doomed, unless workers there accept Mexican wages. Sorry. You can't grow avacados in Michigan, either, because that is also too expensive to be price competitive. Paying avacado farm workers in Michigan more makes this problem worse, not better, for all of the same reasons.
Which part of that whole story is so hard to grasp? I totally get the transparent motivations behind protectionist policies, I just think they are overly simplistic and short-sighted self interest. In reality, protectionist policies make things worse instead of better.
Like you, I also want to support the US economy. I also want good jobs, and high wages, and widespread prosperity for every economic class. Protectionism accomplishes none of that, unfortunately.
Protectionism is a seductive lie that politicians tell to unemployed factory workers to get their votes, without mentioning that it would only destroy our economy even further.