The structure chosen by the city planners years ago literally makes the big box store feasible to economically exist, and reduces the feasibility of mom and pop stores with healthier options. Besides encouraging terrible food options, this situation has generated numerous other social and health-related problems.
Take a walk in the poorest neighborhood in your region which has small-width streets, walking distance between homes and stores, stores on the sidewalk, and terrible parking options. In that neighborhood, you will find fruits and vegetables being sold by mom and pops, and far less prominence of dollar stores.