Cooking real food, as you put it, is just fine and dandy, but there is no way the entire population of the US can survive on only locally grown food. Not everybody has a backyard garden or access to local farmers, nor can they afford to pay more for food than they already are.
They can afford to buy American. I buy American, I cook, and this year I am buying in-season and preserving because things are getting strange with supply-chain uncertainty and hacks. Buying in-season has long been recognized as a good way to cut the family food bill.
Buy a pepper in season and they are $.99 each or maybe even $.49. Buy out of season and you are looking at prices more like $1.49-$2.99.
I go to farmers markets where I can, but not the fancy ones that tend to have fresh baked goods and specialty fare. My farm stand purchases tend to consist of things like bushels of fruit and veggie seconds because I can then can them affordably.
I do live in an urban food desert, but just a few steps over the city line are grocery stores and Walmart super-centers. There are also farms in the county that have stands during the growing season. I do have a garden.
Amy Dacyczyn has a number of books out and the edition that combines vol 1 & 2 of her Tightwad Gazette contains a section of recipes for convenience foods as well as casseroles with cost breakdowns of her versions vs the branded products. Its a bit out of date but you can save a lot of money following her recipes, with in-season American grown food.