i lived in one of those small towns through highschool, just a blinking yellow light and a gas station. What we did, and everyone did, was drive the 20miles to the large town with a Walmart and get groceries there. It only takes 20min because there's no lights or traffic in those areas so the time commitment is about the same as living in a city. My mom made meals from her recipes using basic ingredients so it's certainly feasible to eat how you want in these areas. Only in the most rare/extreme cases are people forced to grocery shop at a gas station.

I've got family in the rural Midwest. It would surprise me if their town wasn't a food desert by these definitions. You might go grab a thing of milk or sliced bread in a pinch at the convenience store, but yeah otherwise you just make the short drive into "the city" to get food at a regular grocery store.

Or you just ate the food you were growing on your own lot, or what your neighbors were growing, or from the farmer selling stuff off the highway.