The food desert problem isn't as grave as it might seem, only because people are in the habit of commuting relatively long distances. T you might switch from grocery a to grocery b, but it's not exactly changing your personal landscape all that much. The fundamental question really here is, how and where and when do people, or better a given person, learn to eat nutritiously? i feel i was very lucky having been conditioned with a palate for generally nutritious food.
Is evolution stacked against healthy eating? What policies could increase demand for nutritious food? And does Popeyes count as a cultural icon?