Doesn't matter the location, what happens when 30% of the jobs are eliminated? How, knowing that, is anyone against a wall to slow down illegal immigration? We'll have a big enough problem with our own citizens due to automation.
automation and outsourcing has already largely happened.
america's economy used to be based on manufacturing. now its low paying service sector jobs. and americans filled them which as you said are mindless jobs (although you should be paid more than min wage for stocking shelves at grocery stores for example). dems and republicans are bought off with money. and now people have sortve figured it out and are voting for peculiars like trump and sanders.
im pro immigration because A western countries abuse the countries these immigrants are coming from, and B i dont believe in being condemned to one country just because you were born in it or not smart enough to legally move elsewhere. thats discriminatory. and the rich already can move to a ton of countries bc theyre rich, but not the poor.
if youre concerned about americas falling standard of living then get politically active which most americans havent done since the 1960s. this anti immigration hysteria is capitalist deflection just like the anti jewish hysteria in germany was.