Was out for a drive today, and saw a shoe (one) laying in the road. It started me wondering why only one shoe?

1. Person got hit by a car and only one shoe fell off?
2. A one legged person get hit by a car?
3. Person was crossing the road and one shoe fell off, and he/she didn't realize it?

Anyone have the correct reason for this? I don't think I'll be able to sleep tonight not knowing the "real" reason!

 

Heard about old news report a few years ago about an old lady who got stabbed in the shoulder by a random attacker and she didn't even realize it until she came home and somebody told her? What is wrong with people these days?