Thing is, Joe Iowa generally can move to cheap third world countries and work in manufacturing there, the work visa rules usually restrict only the opposite movement of labor - it's just that it would be a really bad deal for him because despite the the much lower cost of living, his working conditions and purchasing parity adjusted income will be much worse than in Iowa.
A USA blue-collar worker can't possibly expect to compete for labor in the global market and keep their current lifestyle - for an illustrative example, many such workers can afford cars and houses, which is a relative luxury if they would have to compete with workers who live in dormitories next to the factory. Someone who's earning $35000/year is in global top 1% in income; and adjusting for purchasing power doesn't change it that much, they'd still be in top 10% globally, and they can stay so relatively wealthy only because (and until!) they don't have to directly compete with all the much poorer laborers of other countries. Any increase in global labor mobility will only make it much worse for Joe Iowa.
A USA blue-collar worker can't possibly expect to compete for labor in the global market and keep their current lifestyle - for an illustrative example, many such workers can afford cars and houses, which is a relative luxury if they would have to compete with workers who live in dormitories next to the factory. Someone who's earning $35000/year is in global top 1% in income; and adjusting for purchasing power doesn't change it that much, they'd still be in top 10% globally, and they can stay so relatively wealthy only because (and until!) they don't have to directly compete with all the much poorer laborers of other countries. Any increase in global labor mobility will only make it much worse for Joe Iowa.