People don't like factory work. Given options, they will choose to do some less physically wearing work that pays more, and pay somebody else to do it.

Robots are the answer to reindustrialize the developed world, but that necessarily keeps industry smaller than services.

I don't think you have set foot in a factory recently.

Factory work isn't generally physically demanding, more tedious & repetitive than anything.

It's air conditioned, generally pays a lot more than minimum wage and has benefits.