Why Do People Rubberneck?
Like IL96M said, it's human nature.
It's the same reason that reality TV and shows like Cops, Americas Most Wanted, Worlds Wildest Police Chases, etc etc are so popular.
They WANT to see someone having a scuffle with a cop.
They WANT to see a dead body all cut up.
Well, they don't, but they do.....if you get what I mean.
It's like a dare; something out of the ordinary.
Sadly, too often, someone elses misfortune becomes someone elses entertainment.
But there's also a positive side. People who drive past a scene of an accident often have the reality of it thrown in their face and they become more aware of their own driving habits.