If this type of surveillance is concerning to you, please look at advocating against it at a local level. Thomas Ptacek [1] has experience and seems very willing to help out. He recently provided a really helpful comment regarding reining in a Flock install in his city. [2]
And as has been mentioned a couple other places in this discussion, please contribute to mapping out license plate readers in OpenStreetMap at https://deflock.me. Ideally someone will create a routing engine which with an option to avoid all known ALPR's while generating a route.