[falcolas]

Unless a red light camera is put on every single intersection with a light, there's still a bias in play, a bias based on who uses the intersections where the cameras are placed.

The busiest roads (and thus those most likely to get cameras) are fed by those who are commuting into town to a day job; not by those who live in-town. This immediately creates a bias based on income; the larger the city and the higher the costs of living in the city, the bigger the bias.