Some… Most…
You’ve made some broad assumptions here. I’ve lived in various neighbordhoods in one of the largest cities in this country and near and far suburbs of the same. Only when I’ve lived in ritzy or trendy areas have I had no issue eating healthy (according to my definition of healthy), and always at significantly greater financial cost.
My guess is either your concerns are less restrictive than mine annd others’ on this thread. Or you’ve been privileged enough to not have a clear perspective on just how large, dispersed and discontinuous, the American “food desert” truly is.