A new system that scans customers' fingerprints and deducts the grocery bill from their bank accounts has taken supermarkets in southwestern Germany by storm and is being picked up by hardware stores, school canteens and even the country's ubiquitous beer gardens.
"Almost a quarter of our customers pay with their fingers," staff at the headquarters of the Edeka supermaket chain, which became the first retail business in Germany to use the new system, told AFP.
Edeka has installed the fingerprint payment system at 70 of its outlets and say some 200 others will soon follow because it has proven a hit with clients.
"At first we thought that only the young who really keep up with the latest technology would be interested, but we were wrong," said Stefan Sewoester from IT Werke, one of the pioneers of fingerprint payment software in Germany.
"Almost two-thirds of the people who use the fingerprint system are 40 and older."
IT Werke has furbished around 150 shops, canteens and pubs with fingerprint scanning machines at a cost of 2,000 euros (2,730 dollars) each.
To sign up for the service, customers must have their fingerprints taken and leave their addresses and banking details with the shop, who can then charge purchases directly to the client's bank account.
"It is a godsend for elderly clients because they do not have to remember their pin-code to pay with their bank cards, or to scratch around for their glasses or cash," Sewoester said.
Georg Meisberger from Globus Warehouse, a hypermarket in St. Wendel near the French border, said he had "customers well over 70 using the system."
The stores believe that it saves more than time in the check-out line because it also cuts out the hidden costs of accepting electronic cash card payments.
If an electronic payment "bounces" because there is not enough money in the customer's account, the bank can charge the shop up to 15 euros for supplying them with the customer's address.
Legal issues tied to fingerprint paying have nonetheless generated a few clouds on the horizon.
Retailers have mulled using the information they get from registered customers for advertising purposes, setting off alarm bells in a nation obsessed with privacy rights.
But a spokeswoman for the data protection authorities in the western state of North Rhine-Westphalia, Bettina Gayk, told AFP that the system posed no legal problems as long as it operated on a voluntary basis.
"As long as customers are free to take it or leave it, there is no legal impediment," she said.
"We naturally advise clients not to give out personal data unconditionally."
There are safety concerns too, however, as experts have pointed out that fingerprints can be forged with the help of silicon.
But Ulrich Binneboessel from the Confederation of German Retailers noted that the shops do not use a full set of fingerprints, making the information useless elsewhere.
And it is unlikely, he said, that thieves would painstakingly forge somebody's fingerprints just to buy bread and milk on his account.
"It is probably easier and more lucrative to empty out an ATM machine in broad daylight."
Fingerprint data profiling has long been used for to control access and for other security purposes in Germany's airports, laboratories and nuclear power plants.
IT Werke plans to keep refining the retail use of the system.
It wants to introduce fingerprint payment in school canteens with an additional feature that might appeal to parents -- they could disable their children's access to junk food