Actually "they" have had a similar capability for a number of years, and "they" have used it too.
Everytime one enters one of the major NY to Chicago "turnpikes" he gets a ticket stamped with the entry time. That ticket has to be surrendered (or I guess one could say he lost it, and accept the maximum toll) and the total time to traverse a known distance can be determined. My father was once riding in a car that was given a ticket for completing the Pennsylvania Turnpike at an average 66 mph. The driver protested that it was only one mph over the limit, and was told that he must have forgotten about all those 35 mph tunnels. (This was circa 1960.)
ML/NJ