Part of this is true, part of this is not.

Stores carry what is demanded of their customers, and they don’t carry what they can’t sell before it goes bad. The food isn’t there because it’s not consumed, and because you can’t buy it, it’s not consumed. Fresh food is expensive and goes bad, it’s too much risk as a small business to carry if you don’t think you can sell it. That’s the issue you often see.

My second point would be the huge number of ethnic markets in low income areas with a tone of fresh fruits and veggies. When consumed, they are carried.

There is a culture of convenience that pushes people to shelf stable meals. Those are quick, and generally unhealthy.

Even in affluent locales, quality base ingredients are noticeably expensive.

Portion size / spoilage / price per unit are also a huge issue for those who are single. I'd have to eat almost the same thing every day to properly use up most highly perishable (good for me) foods before they spoil.

I am single, and I generally do not have much of an issue with that here in Germany. "Loose" fruit and vegetables[0] and "single-sized" packaged stuff[1] is widely available without much of a price difference. I rarely have to throw anything out because it spoiled, and I don't have to eat the same stuff for days on end, either.

Is that really such an issue where you live? Interesting.

[0] "Loose" stuff is usually sold by weight, there are scales in the supermarket where you weigh whatever you intent to buy, so buying small quantities has no surcharge at all.

[1] Smaller packages usually are a little bit more expensive than "family size" ones. But I hardly buy anything perishable in such packages anyway. It's mostly things like noodles or cereal, which if stored correctly, can last for months if need be, so buying a cheaper family-size pack as a single is not an issue for me.