But to balance that argument it needs to be said that the range of products and services available through the terminals is growing rapidly, and each offers c-store retailers a new opportunity to build footfall and sales.
PayPoint's retail director Mike Igoe says: "We are working hard to improve margins, but we also provide a lot of ways to increase business."
Recent gains to the PayPoint product family include deals with TV licensing, Littlewoods Pools, Easy Mobile, and Nigerian and Jamaican mobile phone operators, whereby UK consumers can buy credits and transfer them to friends overseas. A gift cards package, through which customers can buy gift vouchers for retailers such as Argos and Debenhams, has been running in Cardiff and is set to roll out.
This service, which is backed up with pos material, carries margins of 5%, as well as giving shoppers a new set of reasons to visit c-stores.
"It creates a whole new category for convenience retailers," says Igoe. "It means c-stores can lead gifting; it's no longer just about secondary and distress. And the range can be extended for other leisure products such as days out and hotel stays. It is a multi-billion dollar business in the US, and has huge potential here."
The basic principle of the payment terminal - that you can load a card with a payment unit to be used almost anywhere else - means that the possibilities are endless. PayPoint has an exclusive partnership with Western Union money transfer and is doing business with all the major bus companies which enables customers to buy their tickets before they travel.
"Travel ticketing is a big win," says Igoe. "It speeds up journeys and means the drivers don't have to carry so much cash."
The rollout of updated terminals, which include touchscreens, contactless readers, thermal printers and a memory, is now complete and further expansion is likely, with PayPoint expected to grow the estate from just over 15,000 to 17,500 by the end of the year. The company also has about 1,500 self-fill ATMs in the UK.
"We don't have a final figure in mind for the number of terminals that should be out there, but we have about 6,000 retailers on the database waiting," says Igoe. "We pride ourselves on the calibre of retailers. We think having a PayPoint terminal is the sign of a quality retailer."
And that combination of quality and quantity gives PayPoint significant leverage, argues Igoe, who is planning to create a 'PayPoint Partner' system to get better deals on consumables such as till rolls and cartridges, commercial items such as insurance and banking, and even savings on travel breaks and meals.
"With more than 15,000 retailers on board, we can negotiate like a multiple chain," he says. "We wouldn't want to step on the toes of the symbol groups, but there are areas where we can get a better deal for retailers." And better deals mean more profits.