Re: Alternative Hypothesis
"In NZ even a stall at a weekend morning farmer's market is risking a significant loss of sales if they don't offer card payment."
You must have very low transaction overheads there. Here in the UK, the vendor has to pay for certification, rental and maintenance agreements on the reader(s), per transaction charges etc. I'm not sure of the exact figure, but most small traders will charge 50p per card transaction otherwise they are losing all (and more!) of their tiny profit margin on low value sales. Better to not sell at all than to lose out on the transaction.
I do also note that the transaction charge for a debit card purchase is significantly lower than a credit card purchase, but small retailers do not make a distinction when adding a transaction charge and that most small retailers do have card processing facilities, very few don't do card sales at all, none that I know of will take a card for less than a fiver. The only people who can operate truly cashless are people who don't care about the "convenience" charge of going cashless and can absorb the likely few hundred quid per year they pay in charges.