Sirens and flashing lights - why do people panic?

I've come to the conclusion that there are three types of driver when it comes to emergency vehicles.
Type I - let's call them the average motorist - are those who respond quite well. They slow down or pull over and leave room for the fire engine or ambulance to get through.
Type II are what I like to call the automobilista nervosa. They're the ones who see the lights or hear the sirens and all common sense goes out the window. They crash into each other, drive up kerbs, mow down pedestrians and generally lose all control of themselves, their vehicles and their common sense.
Type III are the blissfully ignorant. These are the same people that can drive from Salt Lake City to Las Vegas with the left hand indicator going. These ones don't use their mirrors, don't see the flashing lights, and don't hear the sirens until it's too late. By which point, they normally single themselves out as the only car that hasn't pulled over (type I) or driven into something (type II), by being the one car stuck in the middle of the intersection blocking traffic and being blitzed by emergency vehicles.

Try to be a type I - it makes everyone's lives so much easier.