Speaking from my experience of serving in the Coast Guard, the rules and regulations are only one part of what one needs to know, there's simply too much for a mortal human being to have it all committed to memory.
Something else to consider, while the finer points of law pertaining to cycling may be important to us as cyclists, its more than likely very low on the list of priorities of what a cop needs to worry about in most jurisdictions. Cops are also first responders, and that can change ones perspective, rights and feelings can seem a lot less important after having to pick up the pieces of an incident a few times.