To be fair, supermarkets and retail establishments that are geographically available options for them are probably mostly thinly-disguised distribution centers for processed foods chock-full of high glycemic index carbohydrates, effectively indistinguishable from candy.
In other words, just another example of why the parents you describe are living in an horrendous food desert. In that, these retailers are really pushing, or hawking, junk food. Non-food, really. Real food may not be attractive to such retailers from a sales perspective. Expensive to source and stock, and unprofitable to sell. But it’s what we all need!
If people will buy healthy food, stores will sell it. Chinatowns across the country sell low-cost veggies, meat, fish, etc.