Okay, if we're narrowing it down to areas where you can't buy lentils, onions, rice and sweet potatoes, and to people who use food banks, then we're talking about a very tiny proportion of the population.
Not that tiny.
I remember a thread on here a while back when some "let's point and stare at poor people" reality programme had been on Channel Four or Five. One of the people on the show had spent their last £5 on a large kebab and chips from the take-away and someone had posted to say that they were appalled, that £5 could have bought so much fresh fruit and veg and a bag of rice and so on. This poster genuinely couldn't understand that not everyone knows how to cook these things, particularly people with chaotic lives or a poor education, and not everyone has the means by which to cook them. They couldn't understand that £5 on a large kebab and chips that could be split between two people that night with a further two portions leftover for lunch the following day was cheaper than getting to a shop that sold low cost nutritious food, buying the ingredients, puttibg money on the meter to run the cooker and the lights while cooking, etc.