Off the top of my head, and not that I don&#x27;t have sympathy for the point you&#x27;re making, but:<p>* Because their individualized incentive to lie --- or, more likely, to retcon a false belief that the light was yellow when it wasn&#x27;t --- is far less than yours. In fact, it probably does not matter to them one way or the other if you win your case; they won&#x27;t lose a penny.<p>* Because they&#x27;re a third-party observer tasked with monitoring your compliance with the traffic light, whereas you drive through hundreds of lights without burning a milliseconds thought on any of them.<p>* Because they&#x27;re trained to monitor compliance with lights, and you&#x27;re not.<p>* Because they&#x27;ve testified repeatedly before the court and have a track record, and you don&#x27;t.<p>* Because given the cohort of people contesting tickets, you&#x27;re statistically likely to be wrong, because so many people contest tickets for bogus reasons.<p>I&#x27;m not trying to argue that the police are always right about traffic tickets (although it <i>is</i> the case that I have less sympathy for people cited for traffic violations than for almost any other offense [and I get cited too!], given the risks that noncompliant driving imposes on everyone else).