Here in Europe, RFID is the default for public AC charging.
It just seems that if the RFID chip would just be integrated in the car and go over the wire instead of over the air, plug to connect would be trivial to make part of the standard.
It doesn't work that way. With rfid cards, you can have several of them, one for each charging network you have a contract with, so you can decide which one to use before charging. How are you going to do that if your car only offers a single id? If you have three contracts with networks and all three offer access to a charger and each of them is the cheapest for a particular duration or amount of charging, which one would be used?
You need mir than a single id. With plug and charge, there's a standard for this whole issue that is already implemented in several cars and chargers. Just use that one.