You buy a product from a store. The store charges you extra. Then they give you “air miles” which they pay for with the extra money they charged you. This induces a hypnotic state of bliss in the customer.
In “The Dark Knight”, the Joker sets up a situation in which there are two ferries, one filled with upstanding citizens of Gotham, and the other with criminals. They each have a detonator linked to explosives on the other ferry. Whoever pushes the button first will be spared but the other boat will blow up killing all of its occupants.
This is the same principle behind air miles. The profitability of the system depends upon the fact that people like me refuse to collect them. Those who do collect air miles are pushing the button: they get the benefit of this surcharge, while I do not. But the truth is, both of us are paying more for products and services because of this idiotic scheme that vendors have induced people to buy into.
The same applies to discount coupons and affinity cards. Do people seriously believe that the store has reduced prices just because they love having you as a customer? The only reason any vendor has to provide a discount to any particular custom with a coupon or an affinity card is because they can charge more to people who are willing to shop there because of the cheap, meaningless thrill of getting a “discount”.