The privacy violation is that the database exists, full stop. I don't think a warrant requirement would be a meaningful barrier, since the data is already part of the camera network operators' database and all sorts of informal or backdoor agreements would easily happen.
Like, all a warrant requirement does is make it so that the police have to talk to a judge before making the searched data part of the evidence against you. It would do nothing to stop the police from fabricating some other pretext to lawfully stop and investigate you - say, parking a police cruiser at the border into the state and whenever the ALPR in that car hits a list of vehicles, stop them for going 0.1 MPH over the limit and the officer says they smell weed.
Like, all a warrant requirement does is make it so that the police have to talk to a judge before making the searched data part of the evidence against you. It would do nothing to stop the police from fabricating some other pretext to lawfully stop and investigate you - say, parking a police cruiser at the border into the state and whenever the ALPR in that car hits a list of vehicles, stop them for going 0.1 MPH over the limit and the officer says they smell weed.