Apple’s new iPhone leasing program (Apple Upgrade), backed by Klarna, still requires a postpaid account with AT&T, T-Mobile, or Verizon—meaning MVNO customers can’t enroll directly. A former Apple carrier-team employee says there are two main reasons: (1) the Big Three pay Apple hundreds of millions annually for promotions and preferential treatment (including exclusivity), and (2) carrier-level postpaid checks help reduce fraud and financial risk.