Let's digress.
I read this frequently in various forms on this forum, and it's always "just so" justification. My own heuristic thought is that "low quality" food (high energy, long shelf-life processed foods) is very cheap because it is produced at scale and can be stored, while "high quality" (fresh products) is not cheap for the opposite reason.
The US has the cheapest food in the world [1]. Expensive food is expensive, but I would bet quality food is cheaper here than anywhere else. The "problem" is that when presented with a cheap, easy, tasty, high calorie food option against a relatively more expensive "quality" option, consumers choose the former because it's cheaper, easier, tastier, and provides more calories. I would bet this is even true when the absolute difference in price is small.
[1] https://www.fastcompany.com/91208387/food-grocery-prices-us-...