Labor in foreign countries like Mexico or China can be looked on as robots, in essence.
They're treated about as well as you'd treat a machine. Keep it running until it breaks down, and then replace it. Maintain low operating costs to turn a maximum profit.
Americans aren't so heartless as that, which leads employers to find some other way to compete with manufacturers who aren't interested in paying a living wage or showing concern for the well-being of the worker.
Hire actual machines. Skip the people.
Number crunching types have determined that the trend exists and it's strong. Manufacturers are investing in machinery to do the work that laborers once did. Then they don't need to hire so many people to make their widgets.
Not good news for the high school drop-outs who figured they could get a job in a factory and make a living. Those jobs are done by gears and rotors that won't go on strike or ask for a raise. Those jobs won't revert back to flesh and bone employees.
The drive is on to increase productivity without taking on more people who would have to be covered by expensive health insurance and employer-paid FICA and Medicare.
Businesses will get used to having fewer bodies around, and the remaining bodies will get used to doing the job of two or three to keep that job.
Unemployment, in that case, would stay high permanently because there would be more people milling around than jobs available for them to fill.
Put them on Prozac and give them televisions for entertainment and Aldous Huxley becomes a genuine seer, a man who predicted the future. Brave New World may have to be moved to the non-fiction section of the bookstores.