if the merchant doesn't charge a creditcard surcharge, and using a credit card is worth 1€ to me, and costs 1.01€/transaction to the merchant. but only 90% of transactions are by credit card. well, then i am better off paying by credit card, since 10% of transactions are subsidising my 1€.
(strangely, in australia, card surcharges became normalised just before cash payments fell off a cliff. credit card transactions have also declined; it's visa/mc debit that have skyrocketed.)
A credit card costs about 3% not 1%. A credit card is a prisoner's dilemma problem where once anyone uses it, the others are pressured to use it also to cut their losses.
(strangely, in australia, card surcharges became normalised just before cash payments fell off a cliff. credit card transactions have also declined; it's visa/mc debit that have skyrocketed.)