Actually, this sounds very much like the initial concept of credit cards (Diner's Club at 1950) - where the "mechanism of payment" is just that, you get identified and they send you the bill afterwards. All the extra complexity of current credit cards such as balance verification and authorization features are just tacked-on workarounds for various risks, but the original core idea (at least as I see it) was essentially about simply identifying which customer should be billed.