In simple language, as long as it is made clear before a product has been purchased or a service has started, it is legal for a business to dictate how it would like to be paid - as long as the other party agrees, of course.
No agreement or notice I found anywhere from Myers.
I thought I'd try to pay by cash, for my own interest.
They did not break the law although I was not advised of their want, until the payment was offered and accepted by me.
Must be contractual law, perhaps an aftermath of the pandemic, although I do remember Coles in 20/21 asking for payment, other than cash.
I'm becoming more and more concerned about privacy, including all on-line and face-face transactions.
This includes all media and on-line platforms.