Except it isn't. All those LPRs (license plate readers) is logged, by both public and private firms and stored for god knows how long. Then the data is used to create temporal databases to know where your car goes and when, extrapolates your patterns.
Currently, the only uses of the private LPR database that I know of are for either reposessions or serving court documents, but I could clearly see private detectives finding the data useful for a multitude of other uses.
Similarly, the state (as in government) can use the traffic camera video feeds networks to identify vehicles in real-time, and find out when the last encounter was and where. The difference here is no warrant is needed, they already have the data, and they can retroactively search their database (which potentially is every second of every traffic camera feed anywhere).
The fact that data may be discarded is a fleeting one, as storage prices come down, and processing power and resolution increases, it will be considered an intelligence "failure" not to have every moment captured, recorded, stored forever, and searchable.