"It was not intended "

Yes it was.

By enabling low-value manufacturing to go to Mexico, high value could stay in the US and Canada - works very well in Europe and Japan.

And US Corporations get to sell more and more products to Mexico - the Mexican Auto market is growing at about 2X the rate Canada's is, the Mexican ejido system of agriculture has been wiped out.

Unfortunately  US governments never invested in the requisite skills training,  so too many "deplorables" lack the skills to manufacture the higher end products.