As soon as you're three steps from your door, they swoop in like buzzards on a dying cow. Meter maids are the people who never got invited to dances in high school. They realize that their existence is pretty much meaningless, so they try to validate it by making everyone else as miserable as they are. It's some kind of sick revenge. For what, we'll never know.
Accountants do the same thing, but that's another column.
I also think a big conspiracy exists between the towing companies and the airport taxi service. I'm sure you've seen those brown and white mini-vans driving around town. You would think that if they were only for transporting people back and forth to the airport you wouldn't see them very much. I'm not a smart man, but I'm fairly confident that not many people need a lift out to the airport on the weekdays. These guys have gotta make a living somehow, so they hooked up with the Towing Mafia.