Evan Schuman's StorefrontBacktalk

Biometric methods other than fingerprints—such as identifying a retinal scan, facial shape or voiceprint—are likely to be explored several years down the road, but such methods are not considered economically viable yet within the razor-thin retail margins in the United States.

Those other methods are currently viewed as more intrusive than fingerprinting, and would probably encounter correspondingly more resistance from consumers. Retailers hope, however, that over time the acceptance of biometrics will increase.

Those U.S. preferences are not globally universal, said Shannon Riordan, the chief marketing officer for biometric authentication vendor Pay By Touch, which makes the system that Piggly Wiggly is using.

“In China, for example, the retina scan is preferable to the finger because they feel [a retina scan] is more sanitary,” Riordan said.

In the United States today, though, getting consumers to accept mere finger-scanning is proving tricky.

“We’re still trying to get over that hurdle of consumer resistance,” Bolt said. “There must be an incentive for the consumer to do it.”

Bolt’s chain has offered free turkeys and other merchandise for consumers who sign up for the finger scans. “The majority of our customer base does not recognize the value [of biometric checkout] to them. Last week, we enrolled 23 customers. But if I could give them something [that gives them an incentive] to enroll, I could enroll another 5,000 in one week,” she said.

Ultimately, there’s only so much a chain can do to make its customers feel comfortable with any new technology. “It will all come together when it becomes the norm rather than some outlying technology,” Bolt said. “It’s just going to take time.”