If illegal immigration was driving the cost of help down, would they be complaining of a lack of laborers to hire? Someone must be hiring all of these illegal immigrants if their presence is suppressing wages in an industry…
There's no minimum wage for illegal immigrants. The higher minimum wage gets, the more incentive there is to draw upon illegal labor markets, particularly the more plentiful the illegal labor units become.
Rural birth rates plummeted so there are fewer potential workers. Add to that the methamphetamine and opioid epidemics and the pool of potential domestic farm workers is tiny. The ones that do the work are the ones that love the lifestyle.
That means that even small farmers lean hard on H-2B to pick up the slack. Interestingly those wages are actually pretty competitive: around $12 an hour plus room and board.
I assume this is due to the low pay to quality of life ratio offered by farming jobs.