Analogy to a salad bar: if it's priced per-pound, everyone eating a half-pound salad may be getting a different value for their expenditure of the same money... depending upon the mix of ingredients they chose. For example, iceberg lettuce in season may cost the deli much less than other more nutritious ingredients.
Some may say that a profit-minded salad bar eater will choose the most expensive ingredients. If enough people profiteer it (which I think may be described as a duty by some political philosophies,) then the salad bar to remain profitable must either remove the more expensive ingredients, raise the price per pound, charge extra for some items, or possibly twiddle with perceived values. Then eventually people complain when the salad bar is all croutons, iceberg lettuce, simulated cheese product, and mystery pink meat.
I have no idea if this actually is relevant, but I do enjoy me some analogies.
