Nope. No key necessary to plug in. I plug in at 8 PM after my peak billing period ends. At least half the time I have dropped the fob on the dresser, and when I push the charge cable, the car first wakes up, then opens. If you think about it, there is no reason to lock someone out of charging your car, as perhaps one car finishes charging, and is able to plug your car in when they are done, without you. Of course, you can't UNplug anyone else.
Since the charge cable broadcasts a signal, any Tesla within range will respond. With the newer charge ports, they will close by themselves in a few minutes, but it's not dangerous to have the port open. There is no power available until the cable signals the car when it's connected. No one is able to put anything into your "tank" or take anything out. So even if the car is of the older type, it's not a big problem to have ports open.
I think the manual may have been upgraded.