Cheap and easy
In New Orleans, the obesity capital of the world, nothing is cheaper and easier than the staple diet of rice and pasta, along with assorted sauces. This is also true throughout the South. Add grits and you have carbohydrate overload.
There is less obesity in New England where the food is blander and soups are more of a staple than rice and pasta.
Tasting good does have a lot to do with it. That's where the bad decisions come in. Fast food has only compounded the problem in these parts.