It's not about not being able to afford but rather how much people are willing to pay. No one does. Ask any chef-restauranteur. For whatever reason, in the USA..we are very resistant to opening our wallets for food needs. Reluctance.. I can't explain why. It's a mystery.
That aside..take this example: http://www.freightfarms.com/blog/data-from-our-growers-opera... ..semi automated hydroponics system. It's easier to crunch numbers here. I would seriously dispute the 'profit' of $39k/container. There is also the cost of the land and insurance(its same for 1-20 acres. About $800/annum. How would they treat a container for ag insurance? Rent for space where it's parked etc. I don't know) and certifications(GAP audits etc). Reliability of market etc. I would put it at about a third of it. Because these guys will probably be competing with the Salinas and half moon bay suppliers. Also note that they are not certified organic and perishables have to move quickly to a very certain market.
And you do have to plonk $85/container.(I would round it off to $100k).
I am just trying to show you how even a little bit of deviation towards farm automation makes things better. Of course, it's also highly risky as it's a closed system. The numbers won't apply to other produce. Grains and certain commodity crops will have to be grown in soil only. So automation has to be robotic solutions and slowly complementing human labour. And ultimately full intelligent automation. That's our only option.
We have reached a certain carrying capacity I feel and scaling food production using human labour to feed the billions of people(and animals that go to feed the billions of people) is soon going to become un feasible. Not just in terms of actual labour logistics and costs but also in terms of environmental costs..not to mention resources like fossil fuel, water etc..plus the pollution that is inherent to food production. It's all going to be about carbon footprint.
That's why local food production is important. For every load of lettuce harvested, there is a cost too to transport, refrigerate and then transport it back again to the shelves of the local greengrocer. Makes no sense. Example: a head of lettuce grown in salinas..not too far away from Palo Alto goes through the entire supply chain distribution trip before it ends up at a Whole Foods in Palo Alto. There is so many inefficiency leaks in terms of energy, costs and time. Probably decreased nutritive value also due to the age of said head of lettuce.
This hand wringing over labour issues..illegal or not is moot...is useless as 'fixing' this problem is not really fixing the real problem.
The solution would have to be re how tech is going to help us automate our farms. Who knows..maybe farms could even become profitable if that happens. And food distribution has to be local.
I don't know if I have digressed from your original point..that food won't be expensive if we raise wages. Perhaps I have..but I hope i have shown some other facets of the problem and how raising wages is really not a solution.