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Why American manufacturing is becoming less efficient
(www.economist.com)
This is a most excellent place for technology news and articles.
I'd wager it's a combo of all of those things, plus we've just lost the innovations that come with running that of wider sector since so many things are done in other countries now. Manufacturing jobs in the US are also considered blue collar, and blue collar is not looked at as an enviable job.
I'd argue that is not the case at all since manufacturing innovation is a commodity sold to the global market. See manufacturing trade shows. The tech is available, the skilled labor doesn't exist in plentiful numbers to exploit such tech readily.