You would be amazed at all the illegal things the cities do to try to keep their coffers full.
I have read many studies that traffic accidents have increased because many of the towns intentionally reduced yellow light time to increase the amount of tickets. This forces a person to quickly decide based on how far they are from the intersection to gun it through the intersection, but with the smaller time they will get nailed. A person who has been nailed this way a couple of times may try to stop quickly (but not have enough time at that speed to stop in time and get rear ended.
Aunt Polgara, I replied specifically to you on this because I liked the Belgariad reference.