If it is simply a matter of getting calories, carbs, and protein into a human gut at the lowest cost, the freegan is going to win

Or die of dysentery because they ate food that was trashed for a reason. (I have friends who will dive, but it's very much an at-your-own-risk proposition.)

Most people see these as ingredients, not food.

Careful with your assumptions. Rice and beans is a staple in most other countries. It's not gourmet, but we're working with a dollar here. I have a breakfast of oatmeal made from those rolled oats and whatever else I feel like adding on top that day. It's less pleasant without cut fruit or ground nuts, but it's food. My only key additive is ground flax seeds for the bowels.

And while "appetizing" was not among the criteria, availability was

Let's not change the ball game, nothing is going to beat fast food on this mark. I'm responding to claim directly made in the title of the submission. I did try to pick items that store well in bulk, though. Up-front costs may seem a bit high, but then you can sit each of them in a sealed plastic container and stave off starvation for another month.

Also, tangential fact, those Red Mill Rolled Oats have a 73% markup over what I get for my house.