The price of food has dropped, but the price of fresh food has risen.
If you live in LA, unless you have the time to go out to one of the farmers markets, its not even possible to buy fresh food. The "fresh" food in the stores isn't fresh. It is usually weeks or even months old. Sometimes it has been on a ship across the ocean stored in a special atmosphere, maybe it "looks fresh" but it isn't. I grew up in Seattle, things are a bit better there, but you still have to drive out of your way to find fresh food. The concept of fresh and the concept of supermarket are just incompatible.
But as you said, fresh food is available in farmer's markets. And if the price of fresh food has risen, it should be possible to make a living growing and selling it.
Except that the majority of people don't seek out fresh food.
It might be possible to make a living growing and selling it, but it is actually quite unrealistic that a sizable portion of the population could choose to start doing so. %100 of the land in the US is owned now. Its not like the fronteir days when anyone who wanted to start a farm could just go out west. If 1 million americans wanted to start a fresh foods farm within driving distance of a city, that wouldn't be possible. The price of land would skyrocket. And that would only be one third of one percent of all Americans. Not even a significant shift. What if 20 or 30 million Americans wanted to make that transition. Is that economically possible in todays world? What if the government were to give anyone who wanted to start a familly farm a million dollars to buy land. Would it be possible then? I don't think so. I think that it isn't about choice. I think that it is litterally impossible for our society to change without the fundamental ideas regarding property rights or urbanization changing.
"So it's not lack of land that stopped them." You're missing a sense of timescale here. For a long time the number of familly farms has been decreasing all across the country. Recently, it has become possible to make a living selling fresh food if you live within driving distance of a city where you can sell the food for a premium. The high cost of a fresh head of letuce in LA in 2016-17 doesn't help a small time farmer in rural Colorado in the 90s.
If you live in LA, unless you have the time to go out to one of the farmers markets, its not even possible to buy fresh food. The "fresh" food in the stores isn't fresh. It is usually weeks or even months old. Sometimes it has been on a ship across the ocean stored in a special atmosphere, maybe it "looks fresh" but it isn't. I grew up in Seattle, things are a bit better there, but you still have to drive out of your way to find fresh food. The concept of fresh and the concept of supermarket are just incompatible.