When stopped for a traffic infraction in the United States most (all?) officers ask for license and registration. They are legally allowed to demand this information on request as a condition of having a drivers license.
My question is why is this information two separate things? Most police agencies have the ability to look this up in the patrol car. All police agencies have the ability to radio back to HQ and have someone at HQ look it up.
Car registration is tied to the license plate anyway. Isn't the presence of a plate or a lookup from a database sufficient to show registration?
Why isn't car registration tied to the license? Most drivers are going to be driving their own car or one registered to a close family member most of the time. Why are two pieces of physical information required? Is there a historical reason? A privacy reason?