Evan Schuman's StorefrontBacktalk

But let’s suppose iPhone and iPad users love Passbook. How can Apple go after NFC payments? The easy part of that problem is sticking a few chips inside the phone. The hard part: making it “just work,” the way Apple’s customers are accustomed to.

Could Apple partner with Google or ISIS or PayPal? That seemed possible a year ago, but not now. Apple really doesn’t want anything to do with Google—it has stripped Google Maps out of iOS and made a point of mocking Google at the event this week. That’s not a prelude to partnership. ISIS has had trouble lining up interested retailers for its Salt Lake City, Utah, and Austin, Texas, trials this summer, and the trials still don’t have a publicly announced start date. That doesn’t build confidence.

And PayPal is the one payments player that really doesn’t need Apple (for that matter, PayPal’s in-store payments don’t even need a phone). Apple likes to have a strong hand in any partnership. With PayPal, Apple wouldn’t have any hand at all.

Besides, neither Google’s nor ISIS’s nor anyone else’s NFC mobile payments are exactly elegant. You can’t use just any payment card, and you have to go through a moderately complex process to acquire, install and activate the card. That’s not Apple-style elegance. With Apple, you buy and activate the iPhone, and then everything else just works.

That suggests Apple won’t cut its own Google- and ISIS-style deals with issuing banks, processing networks and retailers, either. If a bank said no, Apple would have to tell users, “Sorry, you can’t use that card—try again.” If a retailer didn’t sign on, that Apple user’s iPhone simply wouldn’t work the way it’s supposed to. That’s anathema to Apple.

But wait—Apple already has 400 million payment-card numbers, one for each iTunes customer (and that includes every iPhone user). Why not just transmit those payment-card numbers to the phone during a mobile-payment transaction, then beam it from the phone to the POS using NFC, so the phone behaves just like a contactless card? It just works, and it works at any retailer where Google Wallet, ISIS or contactless plastic cards are accepted—no special retailer cooperation required.

That might work, and it would be the easiest path for retailers: no POS software changes required. But it would cut Apple completely out of the mobile-payments loop. There might also be PCI issues. And the first issuing bank that complained about Apple using iTunes account information for something other than iTunes purchases could turn Apple’s elegant kludge into a sorry legal mess.

Of course, Apple could make sure customers sign off on the use of their payment cards when they sign up for an Apple mobile-payments scheme. That’s fine for new customers (and because no current iPhones have NFC built in, every NFC payments customer will be buying a new phone).

But Apple will need NFC phones out there testing before customers can use mobile payments—remember, it all has to just work.