"The side that stays within its fortifications is beaten." ~Napoleon
"It's always reassuring to find you've made the right enemies." -- William J. Donovan
Illegal immigrant labor, I have no argument with you. Legal immigrant labor is a function of policy, and maybe that policy is crap in some regards, but this balance you speak of is on a knife's edge. It is easy to embrace one element of protectionism, then world reacts to it in a way you don't want them to, and then the protectionist country's only recourse is more protectionism and trade war, and then you have a positive feedback loop. We could go down that path and be self-sufficient cut off from the rest of the world, but our living standards would plummet relative to what we enjoy now.There is a balance. A balance at which we, as a nation can produce the goods and services we need without under the table immigrant labor or labor of nations that pay near nothing.
The answer is - the degree of globalization has changed. Every POTUS in my lifetime has pushed for increased globalization, almost always in direct opposition to the will of the people.