because some other driver HAS to get to the next red light faster than me
I just want to elaborate on this a bit. A lot of times this is not the case, and is a self-fulfilling prophecy for people who drive excessively slow. When I get stuck behind the guy that does 5-under and takes 10 seconds to get up to 40mph, I will hit *every* single red light on a westward route in my part of the city, which are spaced about a mile apart, on a two-lane road where I can't pass. That's because these lights are timed for traffic at the speed limit for 10 cars at a light. If I'm not behind that guy, I hit one red light and 6 green lights. Sometimes its not that they have to go faster, its that they know the light timings better. Its a 5-7 minute difference in my commute. The person's behavior, in this case, actually causes more traffic and a higher chance of accidents than driving at the posted speed limit or 5-over. This also happens in two other places I frequently drive.