Because we are a tribal people and don't want to be invaded by foreigners. Additionally, adding to the labor supply and suppressing wages does not help families afford to have more children. A nation should boost its domestic birth rate, and if there's a cultural problem that pushes towards declining birth rates, they should address that. Bringing in new people is not a solution it is just another problem.
This would probably come as a surprise to the likes of Mitt Romney and Donald Trump (different though they may be, there's a reason they share a political party). I've often heard the slogan, "run the government like a business" which should tell you something. And though Trump may use nativist rhetoric he never had any qualms about hiring guest workers for his own businesses.
All that is to say, while there is a constituency for such feelings, there are no real representatives for it in government.
Ok? I know you don't support those two, so why use their ideas as defense of your position? They are fools all the same, if that's how they govern and what they promote.
I'm not aware of a position that I took in that last comment. It was mostly a comment about the views of the owners of capital in America. They may be fools, but their opinions are the greatest force shaping American governance, especially now that they've greatly advanced their vision of replacing the judiciary in the US (who are now the de facto legislators), so it's important to know where they're coming from.
My own views tend toward the pragmatic - when the time comes to replace my roof, I just want someone who can do the job, because I sure don't want to.