Honestly this is only slightly true. Beans are 2 bucks a pound, cabbage is 2 bucks a head, bananas are 50 cents a pound, chicken is 4 bucks a pound, lentils are 2 bucks a pound, broccoli is 3 bucks a pound, yams are 1.5 bucks a pound, green bell peppers are 1 each, peanuts are 4.5 a pound, etc.

You get my point but I think it's more of a culture and convenience thing.