Maybe Tesla should consider the following: All the time passed the point your battery is charged is deducted from you next charging session.
For example: Your battery charges in 30 minutes, but you stay at the station for an hour (30 minutes of charging + 30 minutes of idling). Next time you go to a charging station you get penalized for a certain amount of time (percentage of you idle time). Of course, this will probably never happen, but it would get the point across!
For example: Your battery charges in 30 minutes, but you stay at the station for an hour (30 minutes of charging + 30 minutes of idling). Next time you go to a charging station you get penalized for a certain amount of time (percentage of you idle time). Of course, this will probably never happen, but it would get the point across!