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Retailers (and some manufacturers) don't have that simplistic of a pricing model. They don't attempt to sell every item at maximum individual profitability; they attempt to achieve the highest overall profitability. For example, selling items as loss-leaders (that is, items that are sold at a loss in order to generate additional sales of other items -- such strategies alter the demand curve for both types of items).
Agreed, but where does loss due to theft enter into the equation?
The optimum price is the optimum price regardless of how many items are stolen.
Going back to my statement, retailers look for overall profitability. If theft reduces the profitability of item A (and thus overall profitability), they will look to recoup their losses by raising the prices of other items. Which items? The items with an inelastic demand (which may or may not include the items being stolen).
Akin to returns and theft being factored into prices and profitability, so are CC fees. Every time us mustachians gleefully get our 1.3% rewards or whatever from the CC, the merchant has paid somewhere on the order of 3-3.5% to the CC company. Therefore prices need to be higher to accommodate this, but at the same time the alternative of not accepting CCs which would result in lower prices, would likely be more than adversarially offset by fewer sales.
So, the prices need to be a certain percentage higher depending on the ratio of people using high reward cards, vs say debit. If no one used these cards, prices could be a bit lower. Because that's not the case though, your most logical course of action is to use a rewards card, exacerbating the problem. Real world example of the Prisoner's dilemma. Best course of action is to help yourself out a bit, while screwing over (marginally) both your fellow consumers (higher prices), and the company (less competitive).
On topic though, I had a friend who has a landscaping business. Would buy a snowblower from Walmart, use it in a commercial fashion all winter, then when it inevitably broke from overuse since they're presumably engineered at that price point for a couple dozen uses per year, not a thousand, return it for a refund.
I'm of a mixed mind about this. He didn't set the rules or invent the game, he's just playing it to his maximum advantage.