Apple's New iOS 8.1 supports Pay. Banks are attracted to Pay.
Near Field Communication is being adopted by many retailers.
The new iPhone 6 (both sizes) have a NFC antenna for secure payments offered through the Pay process. This is linked to the Passbook app. Because Apple has pushed the NFC technology there are many venues, retailers, and banks getting on board.
Banks just naturally want secure, non-hackable transactions. And Pay provides the wireless link between the iPhone and NFC reader. The beauty is in the fingerprint scan on the phone as the device is brought near to the NFC reader.
The credit or debit card that you have set up for the transaction is never handled by the clerk at the cash register. The card's security code is never exposed, and a special one-time dynamic security code is created for that one transaction. That special code then evaporates, never to be seen again. Your card is therefore non-hackable.
Many pundits are predicting that iPhone sales will increase immensely based on secure payment technology that no other smart phone offers. End-users want the best that new technology has to offer, and Apple's new iPhone 6 has that.