Comment It's very attractive (Score 1) 50
You don't monitor all the ALPR in the nation live - you set up a system where every ALPR installation has a 'wanted' database and reports hits. Typically the list would be updated daily and be built from a mix of local, state/province, and federal records. The systems have a mandatory retention policy to only keep hits against the wanted list.
But then you get somebody who catches on to the great idea that it should be retroactive. Force all those endpoints to hold their plate data for as long as the storage holds out - so you can search for where a plate has gone over the course of the last few weeks, or months... hell, maybe years. And you don't just watch for hits against the wanted list, you want to be able to send out queries like, "select all plates in common between these sites and dates" so you can find what vehicle was at every similar crime you've just figured out is probably the work of the same person or crew.
Then they want to throw the retention idea out the window and put cameras at every intersection and highway on or off ramp, and nobody involved worries about how that's absolutely going to be abused by everyone who has access to it.