PayPal's approach with Home Depot and other retailers allows an in-store buyer to input a mobile phone number and PIN on a terminal keypad to authorize a payment, while Starbucks scans barcodes on a smartphone with an optical scanner much the same way Apple's Passbook works.

While Starbucks has been using its optical scanning of barcodes on smartphones for more than a year, its impact on the public's perception of mobile wallets doesn't seem to have been picked up in opinion surveys such as the recent one by creditdonkey.com.

"I expect that context-aware mobile payments like Square and Starbucks will have a much bigger impact on U.S. mobile payments through 2014 than any NFC-enabled attempts," Litan said.

Rick Oglesby, an analyst at Aite Group, said the ISIS decision to delay the rolling out of its NFC approach shows how difficult the process can be.

"Even for ISIS, it's a huge challenge, as we've seen with the delay in launching within two finite geographic areas," he said. "If ISIS is struggling in Salt Lake City and Austin, how could Apple be successful globally?"