I think you completely misunderstood my comment. If you have an hour of video footage of a blue car that you happen to collect from an aircraft while tracking a suspect then on it's own that says vary little. Historically you need to track a suspect to there car and then follow a car so together it's vary labor intensive to track large numbers of people.
However, if the blue car passed a license plate reader it stops being a random blue car and becomes license plate ABC-1234 registered to someone and your now "following" that specific car plus the original subjects car for that hour. Basicly, the readers enable you to track people not just where the reader physically is but wherever you have footage either leading up to that scan or after the fact. Together you can potentally follow millions of people for fairly low costs.
Granted, nothing says the person who the car is registered to is the actual driver, but you have someone who can probably tell you who was driving that car.
And how do they automatically detect the criminal wrongdoing being committed by that car or its occupants? That is the part I don't get. Yes if they decide to look for John Smith, License plate 1AMJ0HN, then they can probably automatically find his car in that footage, and they can watch that footage to see what he was up to. But watching that footage and figuring out if he did anything they can prosecute him for is not a simple task for any computer algorithm I can think of, and would require time to do manually. And with out doing it in an automated manner they can't possibly do this for 'everyone' which means they have to have reason to already suspect the people they do choose.
I see absolutely no way that bringing up the existence of license plate scanners created a situation where there was no slippery slope.
Also the recorded video collection grows to be a ridiculously large amount of data over time, even detecting all video of John Smith's car across the United States will become an expensive task to complete computationally. And for everyone? Well even more expensive.
Add on the concept that camera's will not be covering all of the United States at times, and if you are just using make, model, and color of cars to track people between license plate readers shell games where similar cars rearrange them selves in tunnels or garages will become extremely effective at defeating surveillance if license plate readers are not basically everywhere.
So in spite of you deciding to bring up license plate readers, and explain how they can be used to assist in tracking with airborne surveillance I still fail to see the relevance of how they ensure that 'everyone' will be monitored.
Did you forget about Speeding or the 1001 other traffic offences? Does anyone observe proper following distance for every second of every trip?
I suspect if you wanted to harass your ex-wife, or a dissident, then overhead footage of their car for a few hours would provide a multitude of crimes.
Sure, if you actually prosecuted everyone that's one thing, but selective enforcement plus mass surveillance is a very powerful and easy to abuse tool and you don't need anywhere near 100% coverage to make this effective.
However, if the blue car passed a license plate reader it stops being a random blue car and becomes license plate ABC-1234 registered to someone and your now "following" that specific car plus the original subjects car for that hour. Basicly, the readers enable you to track people not just where the reader physically is but wherever you have footage either leading up to that scan or after the fact. Together you can potentally follow millions of people for fairly low costs.
Granted, nothing says the person who the car is registered to is the actual driver, but you have someone who can probably tell you who was driving that car.