She's noticed a lot of weird dissonances in the way people think about grocery pricing over the years I've known her. For example, despite its reputation, Whole Foods has some of the cheapest prices on staple pantry items in the city. Things like flour, sugar, eggs, butter, olive oil, milk, and rice, as well as many of the "365" branded packaged products are actually much cheaper than "low end" grocery stores like Gristedes or Key Food. Trader Joe's has a reputation as a high end grocery as well, but they have incredibly cheap produce and other perishables. If you go to Gristedes and buy a box of corn flakes you're going to spend $4-6. For that price you can buy 24 eggs! At Key Food you can buy pork chops for $2 / pound. Canned beans and other non-perishables can also be incredibly cheap. With the exception of the corn flakes, which - while delicious - is actually loaded with corn syrup - everything I just listed is perfectly healthy when prepared at home.
Anecdotally, my mother spends an absolute fortune on nasty weight watchers meals because she believes they are "healthier" than just cooking herself a piece of chicken and some broccoli. My sister will eat a $3 lara bar that is "made with real fruit!" instead of a 25c banana.
It doesn't surprise me that within the universe of packaged foods, people think that the expensive ones are healthier than the cheap ones. But I just wish people would figure out that within the universe of foods, the packaged ones are both more expensive and typically less healthy than cooking your own food.