That doesn't even go far enough to cover it.
The citizen is assumed to be an innocent minding his own business. The police officer is an agent of the state. More accountability to the officer.
The citizen is not in a law-related profession, the policeman is. More accountability to the professional than to the amateur.
The officer initiates the encounter. The citizen would have merely driven merrily on his way. Greater accountability should attach to the person taking the initiative and initiating contact.
Excellent points.