The pschology of marketing food in fascinating. Regular grocery stores are laid out in such a manner as to force you to walk past a lot of high-yield convenience foods, which are more profitable for the store...one your way to the few things you probably actually NEED. A store like Dollar General is probably selling them mostly just to get people into their store, so having them conveniently displayed is a plus to them.
I read a really good book on food merchandising a long time ago - I think it was called The Supermarket Handbook. It explained that, in general, fresher and more basic items are sold around the periphery of the store. Dairy, bakery, produce, meats, etc., are usually on the outside loop, with snack foods, mixes, etc. ,on the inside aisles.
The strategy for improving nutrition at lesser cost was thus to avoid the inner display areas fo the store. There is also a lot fo jockeying for eye level position on shelving - vendors actually pay the store for this position - so scan higher and lower, to find better values.
