I had something similar happen to me in two different instances. It wasn't with my truck but with my wife's new Jetta.
I saw this mom once open her back door on her subaru to put her kid in the car, and "BANG", just bounced the door off the side of our car leaving a nice dent. She didn't even show any reaction to what she did. She was just going to get in her car and drive off until I came over and said something. The result was she knew she had banged the door against the side of our car and she does it all the time, but in her mind stuff like that always happens and is unavoidable (her car was looking pretty bad for a new subaru -- got plenty of abuse) so why bother telling anyone...
Another time I was sitting at a light in Fremont in the Jetta (if you've ever spent time in Seattle you'd know that Fremont is an area where there's a lot of bicycles and hippies). This guy comes flying up the center line on a 10-speed passing all the cars, and his handle takes out my driver's side mirror. I roll my window down to talk to him, and he says "sorry, dude", and rides off. I couldn't catch him, so I had to shell out the $200 to fix his mistake.
I don't think most people even think about how much time, energy and $ it takes to keep a car or truck looking nice. If they do then they don't want to be caught wrecking someone elses stuff, so they take off. Very disrespectful. I feel your pain.