I have a lot of experience with food insecurity and have since I was a child. I lived with my older sister and my single mom in a trailer that didn't even have a working fridge so we didn't have the option to store healthy options for long period of times, and we lived in a rural area far from a grocery store because my mom split her time working as a farm hand and a waitress. Sometimes she would bring home leftovers from her job but it wasn't really enough for three people and it definitely wasn't what you would consider healthy.

Food stamps are much harder to qualify for than you would expect, at least in my state. "Fairly inexpensive" to you is not the same as "affordable" to other people. You also have to consider the sheer amount of time and management that goes into cooking and planning "healthy" meals. The majority of households in the US don't have the luxury of someone with the time to manage that because everyone is working, at least full time if not more and trying to live their lives on top of that. You also need to consider that there are people who live in food deserts who may only have access to stores with limited inventories, and don't have access to cars or even public transportation.