We did not import many consumer goods 30 years ago. We had factories making those things. Perhaps they were inefficient. Yes, they could have been automated and productivity increased but the NWO Globalists, i.e. "Captains of Industry", decided that instead of automating USA's factories, like you did in your example, it was better to get 3rd peasants working under God knows what conditions to make our products and ship them back duty free.
The key was a corrupt Federal Govt that has kept import duties so low for so long. It is the linchpin of this NWO scheme to strip mine American industry.
The very liberal(crazy) VICE channel did an investigation and actually went to a port at long Beach CA. He actually talked to the dock workers. Containers full of cargo(consumer goods) from China and elsewhere arrive daily and what do we send back? Mostly empty containers. The bulk of the exports are recyclable material. This is the road to poverty my friend. He summed it up by saying that the USA's chief export is empty containers. This first hand reporting not some bogus study.