I think it was related to this:
http://en.wikipedia.org/wiki/Personal_space,
http://en.wikipedia.org/wiki/Proxemics
People have their preferred public and social distances, and intruding into them causes anxiety. If the waiting room is full then there's good reason to not feel anxious about someone in your personal space, but if the waiting room is empty, then the other person is invading your personal space for some unknown reason.
So parking far away is to try and play on this. People that park right next to the car parked far away probably do it on purpose to antagonize . I've never done it (or even thought about it in either direction), anyone done it?