I've worked a wide array of blue collar jobs and manufacturing I always found some of the worst, even worse than stuff like general labor building houses or working on fishing trawlers in the Bering sea because at least that stuff wasn't nearly as rote.
You stand at a machine doing the same fucking thing over and over. Do one thing wrong, your finger gets chopped up -- you think that sounds easy but wait until you're up all night taking care of a screaming infant and then have to come in so your family doesn't starve, then you make a simple mistake and now part of your body is gone. Often a overnight shift. I would find myself waking up at 2,3 am moving my arms but completely unconscious. Sometimes I would catch myself before I stick my hand into something that would break it apart. One place I was working, about half the people were missing fingers.
I don't know why on earth you would want to bring back people getting burned alive in steel mills or their fingers chopped up when a stamping machine has all its safeties break because maintenance didn't maintain them right. Why we would trade away our comparative advantage in things like designing widgets and instead do the awful work making them is beyond me unless you are so desperate it's your only option.