Evan Schuman's StorefrontBacktalk

But it does push some of the complexity directly onto large chains if they’d like to do something a little fancier than just getting customers to use their mobile phones instead of contactless cards (and considering that most customers don’t even know they’re carrying contactless cards, that’s going to be a tough sell).

Think of it as the Google model—customers pay using their phones and Google pushes ads and coupons, tracks purchases and issues E-receipts—only without Google in the middle. A customer could pay using a payment-card app on the phone, but it will just look like a contactless card to your POS.

To do something more, each retailer will need to create its own in-store shopping app, then make the appropriate adjustments to its POS systems to push out loyalty-card numbers, issue E-receipts and dish out any discounts or coupons. Retailers each get to do it their own way—but they also have to do it their own way.

That may not sound very appealing, but so far the results on non-retailer-driven mobile wallets haven’t been encouraging. The closest to a really popular mobile-payment option for big retailers is the one for Starbucks, which has clearly been driven by the chain. Nobody uses the iPhone (or Android or BlackBerry or Windows Phone) to pay for their coffee—they use the Starbucks app. (And they use it a lot.)

Microsoft may simply be taking the easiest path by handing off the hard work to retailers, banks and mobile operators. Of course, Microsoft may also hope to get into mobile wallets the easy way, and later try to carve off a bigger piece of the pie—much like Apple seems to be doing.

Or maybe Google will offer chains an easy way to add Google Wallet functionality to their apps, so the retailer’s Windows Phone app will work with the special CRM features that Google subsidized in all those POS modifications. So effectively, Google Wallet would be embedded in a retailer’s app, which would be embedded in the Microsoft Wallet. That could make things a little simpler in practice, even if conceptually it’s the messiest payment system imaginable.

Still, all this may be moot if someone besides Starbucks doesn’t goose customers in the direction of paying with their phones. Google hasn’t done it. Neither has PayPal, and ISIS isn’t looking likely (we’re still waiting to hear that its Salt Lake City and Austin trials have started).

It’s clear that Microsoft won’t be doing it, either. If chains want mobile payments, they may have to do it themselves.