We love distancing ourselves from people who give us a bad name. Brunettes tell "blonde jokes" so that airheads of a darker hair tone do not get a bad rep. Band geeks try to set themselves apart from sci-fi convention nerds, even though the rest of the population sees them as the same thing. The biggest reference to this disassociation technique is referring to a bad driver by his or her car.
I'm sure you know what I mean by this. Say you're driving along and steadily approach a red Chevy Tahoe that is driving in the left lane. You have enough room in the right lane before you reach a semi, so you punch the accelerator and attempt to pass. As you start to pull past the SUV--driven by a casually dressed, middle-aged man driving with his wife and children (this distinction will be important in a moment)--he suddenly accelerates and you fear you will be boxed out by the SUV before you reach the semi. You try to speed up even more, hoping you can slip in at the last second, and the family man matches your speed, making it apparent that he doesn't want you to pass him. You give the gas pedal one last push hoping it will be enough, but it isn't and you have to slam on the breaks to avoid crashing into the back of the semi.
Now let's go back to the man driving the SUV. As stated earlier, he is an average Joe driving with his family. He probably has the same troubles and concerns as every other American, and he gets excited about the same things as well. But none of these things cross our minds as we vehemently yell, "What the f***, TAHOE?!" We refuse to believe that this human being who would betray common highway courtesy so blatantly could be anything like us.
And of course we never think of ourselves this harshly when we are guilty of the same interstate discourtesies. The circumstances are always different between us being a jackass or the guy next to us being a jackass. And so it is on the open road, where it's a collective free-for-all for the fastest time to our destination, and each individual thinks their right-of-way is more important than the next's. Being able to cast off poor drivers as less-than-human gives us the feeling that we are the righteous ones. And as far as I'm concerned, I'm never a bad driver. Now get the hell out of my way, Honda!