This may have changed with software updates, but I believe this is true only when the car is unlocked -- that is, when you have your phone-as-key with you, when a door is open, etc. Presumably it's done this way to prevent theft of adapters, or random people coming along and unplugging cars that are charging in public places using NACS plugs. (Using a J1772 adapter, of course, the J1772 plug can be removed from the adapter unless it's padlocked in place.)