Tesla:

We envision a future where cars move themselves once fully charged, enhancing network efficiency and the customer experience even further. Until then, we ask that vehicles be moved from the Supercharger once fully charged. A customer would never leave a car parked by the pump at a gas station and the same thinking applies with Superchargers.
 
 The Tesla app allows owners to remotely monitor their vehicle, alerting them when their charge is nearly complete and again once fully charged. For every additional minute a car remains connected to the Supercharger, it will incur a $0.40 idle fee. If the car is moved within 5 minutes, the fee is waived. To be clear, this change is purely about increasing customer happiness and we hope to never make any money from it.
 
 We’re excited to increase availability during long distance travel and think this change will make the Supercharging experience far better for everyone.