Many mobile payments vendors pile on features to set themselves apart, but Push for Pizza has a different philosophy. It lets consumers purchase a pizza, and that's it.

The iPhone app formally launched Aug. 5 and got 7,000 downloads in its first 12 hours. The app stores the user's preferred pizzeria and payment card, and enables subsequent purchases (including tipping the delivery driver) by simply tapping an icon on the app. The only choice the user has to make is whether to get plain or pepperoni.

"We've taken the entire idea of calling and ordering, which there are many problems with, and made it very simple because people appreciate simplicity," said Max Hellerstein, co-founder of Simple Food Solutions LLC, the company behind Push for Pizza.

The process is similar to what Google demonstrated when it launched its Android Wear smartwatch line in June. The Eat24 Android Wear app can alert users when it thinks they want to order a pizza, and then let them place the order using stored payment info within 20 seconds, according to Google.

Domino's debuted its own ordering app in 2011, and by the end of last year was getting a third of its digital orders through mobile devices. It added Google Wallet support in April.

The appeal of these apps is less about consumers' appetite for pizza and more about their appetite for simplicity when making a payment.

"Technology has always been about simplifying things," said Rick Oglesby, senior analyst at Double Diamond Group. "Simplicity is where it's at, and it's here to stay."

Consumers seem to be drawn to simple — and slightly silly — one-feature apps. The success of apps like Yo (which just says "Yo" to friends) and copycat apps such as the" Game of Thrones"-themed Hodor app (which, like the character Hodor, just says "Hodor") demonstrates an underlying desire to remove the bells and whistles from any mobile interaction.

In the example of Push for Pizza, Hellerstein laments on the issues of giving names and addresses over the phone, which can be burdensome and time-consuming, especially with long names that aren't spelled how they sound. 

Push for Pizza allows consumers to store these details to speed the process of ordering from 1,200 pizzerias. The company was able to launch with national coverage by using Ordr.in's application programming interface (API).

"The concept of frictionless commerce and one-click buying is viewed as ideal," Oglesby said. "In the e-commerce world and particularly in the m-commerce world, reducing the payment action to an absolute minimum is the most desired outcome. In the offline world, the environmental differences require a different approach, and the ideal approach hasn't yet been identified, but the goal will be similar."

Mobile wallet providers are experimenting with a range of technologies including QR codes, Near Field Communication (NFC), GPS location tracking and Bluetooth beacons. But the best practice might be to decide on one simple payment method and stick with it.

Starbucks, the poster child for mobile payments, is a prime example of how targeting a niche market with a simple product can pay off. Users link a prepaid reloadable card to the Starbucks app, which presents a bar code for the barista to scan. Mobile payments account for more than 15% of transactions at U.S. Starbucks stores, up from 10% a year ago.

"Right now the multi-merchant/multi-purpose wallet solution is aspirational, but single merchant/single purpose solutions can work," said Oglesby. "At some point we may reach a limit to the number of single purpose solutions a consumer will [tolerate] … but we can’t assume that the constraints of the physical world will apply in the digital world."

A physical wallet can store only so many cards, but a smartphone can store as many pizza and coffee apps as the user desires, he said.

The Push for Pizza team is working on an Android version of its app, which it expects to launch in mid-September. It is also planning to support more pizza varieties, well as build its own database and expand to other categories. Hellerstein has his eye on bringing the same simplicity to ordering a burger, for example.