But this point conveniently overlooks what the farmers do in response to this lack of labor: they literally let crops rot in the fields and lose a lot of money.

It simply is not economical to pay that much higher wages given the low prices people want to pay for produce, and they waste anywhere from 30% to a full years' worth of crops. Forget "preserving margins," they typically straight up take a huge financial loss on their investments up to that point.

So really, it's not just a simplistic choice between cheap immigrant labor or expensive native labor, it is also about farmers actually having a viable business, and everyone getting affordable produce -- very often, including people who really need that food: https://calmatters.org/california-divide/2019/10/california-...

I don't know what the actual economics are, but it's very conceivable that, after considering all the people involved, it is better for cheap immigrant workers to undercut expensive native workers as long as the majority of people get more affordable food and farmers can keep their businesses going.