There's plenty of high quality food, you just have to know where to look. For example, come to the Bay Area and check out Whole Foods and any number of high-end restaurants.
The problem isn't that people go to supermarkets and they can't find any healthful ingredients to cook with. The problem is that they go to supermarkets and pass those over in favor of convenience foods that have been optimized for "craveability" [1].
GLP-1 drugs can alter this behavior by reducing food cravings. Someone who's no longer craving the most craveable food can make more objective by-the-numbers buying decisions the next time they go grocery shopping.
[1] https://www.npr.org/sections/thesalt/2015/12/16/459981099/ho...
There are also native stores that are increasingly entering into low cost produce like Grocery Outlet and then there are the usual like Food4Less but they tend to eventually move upmarket.
The only way you're going to get high quality food in the US is if you live where the Amish are.