I was taught when getting my permit that a traffic cop overrides a traffic light/ or driving sign
Yep. The goal is to drive safely while also not impeding the flow of traffic. If only doing the speed limit is safe for someone, they should probably make their way to the right lane and especially if they see a line of cars mainly only behind them and definitely if they notice people constantly coming to pass them from the next lane over.
It's easy to get your permit/license, but defensive driving is a learned skill acquired through experience. Gotta be able to pay attention to patterns and behaviors or you're no safer than someone driving 30 over on a completely empty highway.
That's why in most rear ending accidents, the rear driver is almost always declared liable even with a dash cam. Chances are high that if more attention was paid, nothing would have happened besides a "look at this a$$hole" and the day would have carried on like normal.