"Value add" is the wrong framework for thinking about these sorts of services. The reason Visa and MasterCard exist is that there's value in relationships. If you want to have your accounting system available in all stores, you have to talk to Visa or MasterCard. Conversely, if you run a store and want to accept payments, you only have to deal with Visa and MasterCard. Sure, "public service", but run by who? Visa and MasterCard are cross border, good luck getting any sort of international coalition of governments to build a payments system in the current political climate.