actually, the airlines dont care because they don't foot the bill for this activity. It is the merchant or the credit card company that pays. The credit card companies pay the airlines for the miles they award in the card programs. (you might recall that last year Amex bought a large chunk of miles from Delta... those miles are the miles Amex gives to carholders). So the airlines would actually make revenue from any such scams, although I doubt the volumes even register on the radar of the airline...