It works if your existing population is willing to do unskilled labour.
Which in my country is not the case
(That is, you'd have to pay them so much they could buy the farm and then hire someone else to work it. But you're not going to do that.)
Promoting a second-tier, legally-disenfranchised workforce isn't the win you seem to think it is.
It doesn't have to be "complete", just a shortfall in demand, and of course eventually it ends. But if the market doesn't clear for a while, that's still people having to eat less for a while.
> Promoting a second-tier, legally-disenfranchised workforce isn't the win you seem to think it is.
Almost everything is better than farm work, which is why everyone ditches it as fast as they can. Even being a sweatshop worker is better. Nevertheless, the migrant farmworkers are doing it because it's better than their alternatives, presumably because they get paid better than doing it in their own country.
Btw, I'm not even thinking of especially poor countries here. Japan is a respectable first-world country but has surprisingly low wages and a bad exchange rate, and there are recent cases of Japanese people leaving for Australia to do work like this and making 2-3x what they can at home.
And of course back in Japan it feels like every convenience store worker these days is an immigrant from China, India or elsewhere.
This is fine, really. Productivity will increase over time, they'll save money over time, and their kids will have better jobs.
The jobs move to distant factories filled with alien staff paying taxes to far away governments and who then spend their wages where they live (which isn't where you live).
Even with tariffs, that's still cheaper for many things. And the work you're incentivising to bring to you with tariffs, that's often automated precisely because it's unskilled. Food has been increasingly automated at least since the 1750s — to the extent that cows milk themselves (into machines not just into calves) these days.
It works until it doesn't — wherever the jobs go gets a rising economic spiral, and a generation later their middle class is corresponding richer and say to each other much what you say now: "why do we need them?", only now you are a "them" in that discussion.
It's a weird thing, migration. The short term incentives absolutely favour it for everyone, but it's bad for the place of origin in the long-term.
But note that I didn't say international migration: the arguments are the same between San Francisco and Sacremento, or between Lampeter and Cardiff, or between Marzahn and Zehlendorf.
So what you want is to import third world immigrants so you can pay your plumber cheaply instead of paying them appriopriately.