Most of us have been there. Our buddies want to go out and have a good time and they ask you to be the designated driver. While they're laughing and carrying on in the back, your stuck having to pay attention to the roads. Oh and the pressure is on you for them to uhh..not die.
While some enjoy being the designated driver and the responsibility, most would just rather put it on someone else and have a good time.
..and thats why there is a tank shortage.