What you are describing is a de facto food desert: https://www.cdc.gov/features/FoodDeserts/index.html
There might be an easy (albeit costly) way to fix this. Just today I learned about a govt agency called the Essential Air Service:
> The United States Department of Transportation (USDOT) subsidizes airlines to serve communities across the country that otherwise would not receive scheduled air service.
https://en.wikipedia.org/wiki/Essential_Air_Service
Because seats are paid for in advance, airlines don't have to worry about route popularity, and that allows them to financially justify serving towns that otherwise would never be considered by any airline.
I wonder if taking the same model and applying it to food a la the Essential Food Service might make sense. If federal or state governments subsidized every grocery store purchase so the owners can afford to keep the lights on, we can stop or even reverse the grocery store death toll and enable shorter commutes for rural residents.