You bring up a valid point. All too often the enforcers (er, cops) are ignorant of the laws they are enforcing. In Maryland there is a law that states that your tires can't stick out beyond your fenders. I recieved an inspection ticket for that infraction, while at the same time, the trooper gave me a ticket for having tinted my rear window (on a pickup truck). No other windows were tinted, but apparently the trooper didn't know that it's not illegal to tint any glass, no matter how dark, anywhere behind the driver's field of view (i.e. anywhere behind the driver/passenger windows). It was easily solved when I got inspected for my fender covers, but had that been the only thing I was ticketed for, I would have been pissed if I had to waste my time getting inspected because of the trooper's ignorance.

Another time I came out to my vehicle, which I had started with an autostart remote, to find a trooper looking over the vehicle, preparing to write another ticket. She told me she would let me go with a warning this time, but if she found my car running again without my being inside, with my foot on the brake pedal, she would ticket me. Little did she know, but the law states that a car cannot be left running WITH THE KEY IN THE IGNITION unless the driver is present, with his/her foot on the brake. Because the autostart doesn't require the key to be in the ignition, and cannot be driven without the key, there was no violation. Another case of ignorance on her part.