NZ already has electronic payment cards that are independent of credit card companies, called EFTPOS, that has been in use since the 80s. The cost off this for shops is a fraction of the cost of credit card transactions, starting somewhere like USD$10 per terminal per month for unlimited transactions of any size. Credit cards often take as much as 1-2% for Mastercard/Visa (the higher fee/higher reward cards US are often not accepted). In fact, credit card fees have become such an issue a large number of places will on-charge the fee to the customer.

If you're a small shop with one terminal paying $10 per month, it's not a cost that really matters. Unlike credit cards that often charge an annual fee to the user in addition to the transaction fee, EFTPOS cards are typically provided by banks free of charge. There is even competition in the space, with two different companies running EFTPOS systems.

Credit cards can generally also be used for EFTPOS so we don't even have to carry two cards around. Given this system, it would be interesting to see how much room there is for a central bank digital currency to improve on it.