[smeagull]

There is nothing saying that a product needs to pay for all the processes inherent in making that particular product.

There is value in having flat pricing across all your products. Especially if some of them aren't as popular, yet might driving purchasing decisions.

Consider cafes that need to stock decaf, but want to buy from a single supplier. If you don't have decaf you're not going to see their custom, despite their order largely being non-decaf.

So they'll want to supply decaf, but in order to encourage the sale of it (so they can reach a better economy of scale) keep the price the same as the equivalent non-decaf.