We don't onshore because we are higher up the economic food chain, and can do more specialized work. The people high up that chain in the US are the same class who conceive of minimum standards for living quality for the whole country, effected by things like minimum wages, welfare, and all manner of government safety regulations.
All of those things make a very small overlap between people who need to work such low value manufacturing jobs and those who have the skills and personality to do them. In essence, we've settled in to enormous wealth and safety by cooperating with other countries, and you are proposing that we should cooperate less and be poorer.
I'm not convinced that you're wrong, but that's what you're propounding.
Update: In other words, you're asking the national level version of "why don't we move back to the land and become self sufficient and steer clear of industrial ag and make our own food?" Same answer: we like our wealth, comfort, and safety where we are, thank you very much.
All of those things make a very small overlap between people who need to work such low value manufacturing jobs and those who have the skills and personality to do them. In essence, we've settled in to enormous wealth and safety by cooperating with other countries, and you are proposing that we should cooperate less and be poorer.
I'm not convinced that you're wrong, but that's what you're propounding.
Update: In other words, you're asking the national level version of "why don't we move back to the land and become self sufficient and steer clear of industrial ag and make our own food?" Same answer: we like our wealth, comfort, and safety where we are, thank you very much.