Do people buy their houses that the bank has given them a loan for? Technically people doing the carrier or Apple's upgrade programs ARE buying the phones, they are just getting a 0% apr loan to do so. A bank has a lien on the house but you own it as your name is on the deed, and they gave you a mortgage loan for it (and doubtfully at 0% apr). When you lease a car, the dealership or leasing company owns the car...their name is on the title.
Practically, the behavior of using the upgrade program may feel like a lease or look like a lease, but it isn't. I suppose some of you though may also be suggesting all those people buying houses, then selling them and buying another, are just renting.
However, who cares if it meets the definition of a lease or a purchase? Gheesks.
Another question for people who are buying their phones outright is why are you not taking advantage of 0% APR? Say your phone costs $1200, why not stick that amount in an interest-earning account and autopay the $50 per month for 2 years....you won't make much but you will make some.

The only reason I could see is if the contract locks you in to a two-year agreement for cell service, but I'm not sure that it does. You can pay the phone off whenever you want.
People who upgrade every year spend way more money than people who only upgrade every 3 or more years, regardless whether they are upgrading every year on the program or buy outright. I'd suggest though that if you are upgrading every 2 years, buying outright every 2 years or not, you may want to look at being on the new phone every year plans. For the price of tax in the off year plus maybe a $30 service fee the cell companies love hooking you for, you get a new phone every year vs buying outright every 2 years.
However, as your financial advisor will tell you, use your phone for 25+ months...maybe even 48 months or more...and you will be "saving" money. In quotes because you cell / data plan is a whole lotta money too. Save money by having a dumb phone, or no phone at all if you really want to.