A hit and run that hit close to home

[sundial]

How can you hit someone and just leave them? I don't understand.

I don't understand it either. It sure makes you wonder if the driver was so preoccupied that he/she didn't even notice hitting the rider. I've noticed just in the last year the number of drivers who are crossing the center line while fiddling with something in the passenger seat or in their hand. People are more preoccupied today than before.