There is definitely a data channel in the Tesla Charger. Not sure if the data is encoded into the charge current or if there is a separate data connection/wire. The internal charging diagnostics communicates with the charger to adjust the current. It takes about 45-60 seconds from plugging the UMC connector in before the current reaches steady state. For the Superchargers, is even more complicated than that so that the Superchargers can bill your account if you don't have free supercharging or won't charge if you do not have a current account with Tesla.
My understanding on Superchargers is that your car actually does all the heavy data lifting. You will have a "yes or no" token onboard for Supercharging capability. If no...no juice.
If yes....Free or no?
If not free....used up credits? no? then, juice....
If credits are used up, then the car will send up to the mothership how much kWh (or time in some places) you took up, and bill you accordingly to the CC on file.
The Supercharger only talks to your car, not the outside world.