Shoes can't drive themselves around, can they?

In lieu of posting on something substantial, topical, or personal, I'd like to take a moment to comment on a pressing and irking matter.

While driving today, I saw a shoe on the highway.

Again.

This shoe-on-road phenomenon seems to be fairly wide-spread, and I cannot figure out why.

How often does someone, while driving, feel the urge to pull off their shoe (or lean over and pull off their passenger's shoe) and eject it from their car? And wouldn't that be dangerous? Similarly, no passenger that I have ever driven has grabbed their shoe (nor my shoe for that matter) while driving and thrown it out the window. As well, in this post-9/11 world, how often do footwear fights actually break out while a vehicle is driving?

Or is this phenomenon indicative of some new form of road rage? Are people trying to throw projectiles to hit other vehicles that cut them off or offend them in some other manner? Or are there that many Khrushchev-philes running around with an extra shoe? (Bonus points to anyone that gets the reference.)