Maybe all police forces are very sophisticated gangs who have figured out that it's better to pretend to be police then to be seen as a biker gang. Otherwise they are braking the law. They give you a ticket if you can not produce them, so they should be required to produce it to you. See my comment above about mutuality of authority. If you want mutual, go see your broker or banker for mutual funds.
Police vehicles fall into the same category.
Not just commercial vehicles, but all vehicles licensed for use on public roads must have ownership and insurance documents, including police vehicles, but so what. As I said before, you have no right to demand that someone else produce those documents to you unless you're a cop exercising authority conferred by the Highway Traffic Act. Only if you're real lucky would you be sitting at the side of the road. If they had, they haven't lived to tell us about it. Just a thought.