I probably can't say this without sounding like a snob. But I am from a family whose parents knew about nutrition and fed me a good diet. I still ended up obese but that's another story!
I am from a privileged background, not a rich one but I have been to university, done two degrees, lived with lots of different people and been around people from much higher social statuses than me, the same, and lower and I have noticed a remarkable difference.
My last two relationships over the past few years were with people who were from a much 'lower' social standing if you will, than me. I don't actually think I am a snob, they were or appeared to be nice people and I had no qualms about dating them.
Both of them had been brought up to eat total crap, continued to eat total crap, and although they didn't have their own children I was around enough to see that the children in their families (their nieces, nephews, great niece/nephews, step children, friends children etc etc) were also fed lots of crap. UPF everything. Constant snacks. They were from impoverished areas with a good sense of community so I saw a lot of other people's kids in the times I was around them too. Everyone ate lots of crap! Seldom saw the toddlers without a sugary drink in their hand.
My most recent relationship, she was reasonably intelligent in comparison to the one before that, who was not so much. Couldn't spell, difficulty communicating, socially awkward, didn't understand most things (we couldn't talk about politics, nutrition, world affairs, name any subject that wasn't football or TV shows) she hadn't read any books, very simple taste in things, very stuck in her ways and her own little world. Most things I cooked, she had never even heard of them. I asked her to pick me up some butterbeans from a supermarket, didn't know what they were. Hadn't heard of sugarsnap peas. Didn't know what stuffed vine leaves were.
I know it is a tiny snapshot, but for both of them it was 'class' rather than intelligence. Following their parents' protocol, going along with what everyone else in their social circle did. I think people of that sort of background, are more attached, more close knit with their communities, than those who are from a different background.
When I was younger a girlfriend of a friend approached me as had heard I was a good cook and wanted some tips to lose weight and be healthier, I remember her actually not knowing what a lentil was, let alone how to cook them.
Some people who have maybe not socialised with people who are from a background beyond their comprehension, do not take these things into account. It's fine telling someone that lentil soup is cheaper to make than chicken nuggets, or that it is easy to make hummus and feed it with crudites and and most kids will quite like it if they're introduced to it rather than nuggets! But that person may have never heard of it. Their sense of community tends to be a lot stronger, they are together with other families, in and out of each other's houses, kids get fed at whoevers' house they are at. It's not easy to make a switch when your lives are like that.