Junk foods like Doritos and Pepperidge Farm cookies are quite expensive. And junk foods have become even more expensive with the decreased usage of trans-fats and HFC.
It's actually cheaper to eat things like beans, rice, grains, and veggies than it is to live off of frozen pizzas, bags of chips, and highly processed specialty foods.
Meat is also more expensive than vegetables. It's much cheaper (and healthier) to feed people with beans, pulses, lentils, etc. than it is with ham or steaks.
Advertising thrives on lies. One of those lies is "junk food is cheaper."
Sure, it's cheaper, if your idea of a healthy meal is to eat a steak.
At near starvation, it is pretty bad on the homeless population, they really have very few alternatives outside of salty pre-packaged "ramen" noodles, McD's (and other fast food chain) dollar menus, and so forth, but for the average person who is at least working class and can cook beans and rice, it's a lie.
A huge, huge lie.
I still think organic foods become cheaper with supply and demand, someone can correct me on this.