The Chatrie case is really relevant to ALPRS. The Chatrie case involves the government demanding private phone GPS location data from Google. This is not covered by the plain view doctrine because the data they're requesting is fundamentally not collected by observations in plain view.
Unlike the phone GPS location data, ALPRs are cameras set up in public locations recording what anyone with their own two eyes and a notepad could observe.
Unlike the phone GPS location data, ALPRs are cameras set up in public locations recording what anyone with their own two eyes and a notepad could observe.