The outlet behind the door is the one used to plug in the vacuum cleaner. This is because all the other outlets are used or are located behind pieces of furniture. I have three bedrooms and the outlet behind the door is always accessible BECAUSE it is behind the door (nothing can be put there because the door wont open otherwise).
Makes sense, maybe all those behind the door for the vacuum outlets should all share a dedicated circuit by themselves. You can only vacuum one room at a time, and it would be good to keep the sparky noisy vacuum cleaner motor away from the computers and TV sets. Place the outlet about 2 feet from the door hinges so you don't have to dig deeply behind the door.
I've had apartments where the apartment's subpanel was placed behind bedroom doors. So tennants couldn't place furnature or bookcases in front of them. So you'd have the required working space for them.
