Cue rash of smashed screens and thus inoperable chargers.  The main reason Tesla's Supercharger network has been so reliable is the fact that there is very little for vandals to damage.  A screen is just the perfect thing for some degenerate to smash.  Wouldn't a very basic LED (segment-type) display suffice?  And even if that were damaged, the machine would still work... Just have a basic 'tap credit card here' instructions printed on the case and a very robust and simple LED status light to tell you payment has been accepted and off you go.  Easy enough to look up what Tesla is charging (if you are the slightest bit interested - most of us are just happy the charger is available and works!) on the WWW.