Even if the police make this data private, the general population will jump in to make this (and most) data such as this freely available. A small box located near your mailbox will be able to record every car that drives by and capture video of anyone walking by.
This technology is already available in the flying world-- where FlightAware makes a plane tracker that publishes flight data from the skies to the public.
Take away lesson is your data will be mined. If you think license plate data is a breach, just wait for ubiquitous facial recognition data going to the public domain.
Brave new world!