In regard to fees, standard Eftpos cards, I.e with a mag stripe only, dont cost merchants anything to accept.
Most banks predominately issue 'scheme debit' cards now, i.e. with a Visa/Mastercard logo, and these cost nothing to accept if the cardholder uses the chip or mag stripe in store and selects cheque or savings. If the card is used for a contactless transaction, or credit, it incurs a fee. Fees are also incurred by merchants when these cards are used for e-commerce.
Mastercard has had a contactless interchange fee for ages, Visa recently introduced contactless rates, previously the fee depended on the type of card used, e.g. platinum/classic.
No doubt a backward step by BK and their customers will probably vote with their feet. There are numerous studies showing the benefit of contactless. In a bar recently it took 30 seconds to process chip transactions. I counted. Big queue for drinks. I said to the barman they need contactless, he said he gets told that dozens of times a day. It's a no brainer in quick service environments, but I understand why Mitre 10 dont offer it.