I've not found any correlation with age, though. I have to say, I've been in the car with people old enough to be my parents who do this. One time, I was in a car with someone on the Garden State Pkwy and they realized they missed the exit, so they decided to slam the brakes, stop, and back up. They were in the center lane when they did this. Let me tell you, I was totally freaking out, man.

On the other hand, many people pull off the side-to-side trick pretty well and without getting in anyone's way. It all depends. And yes, people are in a rush, often with good reasons and intentions but it's not always their own planning that is to blame.