Perhaps because they can claim iTunes, because of the iTunes Store isn't an end-product so much as a platform upon which people make purchases. They can account

Perhaps because they can claim iTunes, because of the iTunes Store isn't an end-product so much as a platform upon which people make purchases. They can account for the revenue from the greater iTunes app through each purchase you make in the store. Same goes with the App Store. Not sure how they deal with people who never purchase anything, but perhaps they don't have to be 100% thorough about it.