Visa et al are going to charge a minimum transaction fee for small-value transactions, which covers the typical charging session. Third party services are an advantage, because they can bundle small transactions together and take advantage of their economies of scale and their own fraud models. There is a world where Visa and the payment card industry looked forward in the year 2005 and said “IoT devices like EVs will need payment capability, let’s think about how to be essential to this ecosystem in a way that removes the need for third party services and saves everyone money” but that kind of technical innovation seems to be outside of their core competency.