Originally Posted by
ethernal
I don't think the rental car comparison is quite right.. usually airports serve a broad area whereas a hotel is usually very localized.
If you were under surveillance by the police or a private investigator, a spook, an investigative journalist, a rival corporation looking for trade secrets or even your wife's divorce lawyer, it would be easy to determine if you were loyal to a certain rental car company. Once I knew that and your travel patterns I could get there before you, see your name on the rental car board and place a recording device inside the car to monitor your activity.