Re:These systems which preach safety and security. (Score 1)

Traffic Management Authorities would jump head over heals for the ability to see real-time position of all cars on the expressway.

They're pretty close already: http://www.southflorida511.com/Cameras.aspx has pretty extreme coverage of highways in South Florida, and it could easily be upgraded to real-time tracking of cars with higher-definition, faster, and more low-light capable cameras. There's already enough camera coverage to do Open Road Tolling, by license plate tracking or an in-car transponder in the same lane.

Relying on each car to transmit their own position correctly isn't something that will work at highway scales; only now is it proving workable for commercial aircraft (see ADS-B).