Brian Krebs wrote recently in Location Privacy: The Purview of the Rich and Indigent:
But according to the Electronic Frontier Foundation (EFF), the data collected by ALPR [automated license plate reader] systems can be very revealing, and in many cities ALPR technology is rapidly outpacing the law.
“By matching your car to a particular time, date and location, and then building a database of that information over time, law enforcement can learn where you work and live, what doctor you go to, which religious services you attend, and who your friends are,” the EFF warns.
That sounds like a familiar set of concerns.
Even if the contract between the state and Vigilant [Solutions] ends, the latter gets to keep all of the license plate data collected by the agency, and potentially sell or license the information to other governments or use it for other purposes.
And, aside from selling a database potentially containing your license plate, where you've been, and when you were there, merely keeping such data makes it vulnerable to a data breach.