Food is a bit different in that we export a fair amount; it's not like we're running up against the limits of what our farmland can produce. For what it's worth I absolutely abhor the phrases "they're more willing to do that work" or "it's work that American's won't do." You're missing the last part of that sentence: for that pay.
Of course costs will go up. So will pay. You're right in that in the case of food it's hard to say how that would all equalize. However, are we to rely on what's essentially an underclass forever? That seems pretty dystopian, and unsustainable.
Home prices I'd argue wouldn't be affected as much. The "dumb" labor in building houses is pretty cheap. Framing, roofing, etc. isn't much of the labor cost and they aren't on the jobsite for that long. Skilled work such as plumbers, electricians, and the like cost much more. There are kind of inbetween jobs such as drywall taping and tiling and I don't know how much of that is done with immigrant labor. In my experience it's basically none but I could be off on that.
I think we probably agree on some of the broad strokes, but interpret the details differently.
Regardless about how much we export, prices are tightly coupled to supply and demand. If your theory holds, we should see a commensurate increase in cost. It doesn't matter if net exports go down unless there are effects from steep tariffs.
I agree that a large part of that many Americans are unwilling to do that work for that pay. And yet they are beneficiaries of that low-pay work in the form of low food costs. I find it particularly unsettling when those who directly benefit simultaneously demonize the immigrants who they derive some of that benefit. However, there have been studies showing that Americans underproduce migrant labor in industries like agriculture. So it's not just the pay, it the ability to produce. Similar work quotes farmers as saying they literally can't hire Americans to do the work. Unless I suppose you want to pay them salaries that risk farms being unsustainable financially. The extension of these points is if you were to hire Americans at an American wage, you get both less production and a higher cost while simultaneously risking the solvency of the farms.
I also agree that the use of an immigrant underclass is dystopian. Especially when you factor in the abuse that occurs in workplaces where employees are fearful of recourse due to their immigration status. And yet it happens and one of the often used excuses is that it's necessary to essentially subsidize a certain quality of life for Americans.
FWIW, it's usually termed "general" labor rather than "dumb" labor. You're point here seems to contradict your previous point that immigration also brings down the wages of skilled jobs. They way they do both is if they are represented in both skilled and unskilled employees.
As far as construction, this is largely region-dependent. (That's why I put the south in the original response. It's especially reliant on immigrant labor.) A rough rule of thumb is that labor is 20-40% of construction cost. Regardless, in my region, immigrants are the bulk of skilled labor as well. Again, anecdotal, but once you peel back the thin veneer, you can see how much of the American lifestyle relies on immigrant labor. And simply banning them in the hope that it increases housing availability will have many second order effects.
Of course costs will go up. So will pay. You're right in that in the case of food it's hard to say how that would all equalize. However, are we to rely on what's essentially an underclass forever? That seems pretty dystopian, and unsustainable.
Home prices I'd argue wouldn't be affected as much. The "dumb" labor in building houses is pretty cheap. Framing, roofing, etc. isn't much of the labor cost and they aren't on the jobsite for that long. Skilled work such as plumbers, electricians, and the like cost much more. There are kind of inbetween jobs such as drywall taping and tiling and I don't know how much of that is done with immigrant labor. In my experience it's basically none but I could be off on that.