Is that really relevant, though? If the cost of having cheap food is that we create an underclass that are willing to put up with low wages out of economic desperation, is that really an acceptable moral compromise?
The people picking chardonnay grapes often aren't the target consumers to begin with, but your core point is correct, wage inflation usually leads to price inflation, but it doesn't always follow that therefore the product becomes unaffordable.
Or more likely you just get automation. We don't use a lot of man hours per lb of corn. Which means even without massive subsidies it would still be dirt cheap.