This system has been around and tested in the BC area for a while. They go into highly populated parking areas and do random checks and find stolen cars.
We also have a similar scarier system in Calgary for parking downtown which entials no coin/cash options and method payments by cell phone or credit card for parking downtown. You put in your plate number and your spot and pay with whatever method you want. Then how they cehck the "meters" is a very scary looking car with several I think about 12 or more cameras on it comes by and scans your plate to see if he needs to give you a ticket or not. Sorry I could not find photos of the car that checks the plates I will try and get some.
But back to the issue of a police force using an automatic dection system I support for sure, no rights are violated and *currently to my knoweldge* they check to see only if the car is stolen or recently reported in a criminal act like dealing drugs adn unlisence/uninsured vechiles. So no rights are violated and criminals (If the system is effective) get caught quicker and go to jail (hopefully but unlikley).
This reminds me to shout out to all wogs in Canada if your in the Law Enforcment/Security industry I have an awesome tool for you guys to use, its called public CPIC and is a online stolen car checker. Though its not updated as frequent as the real CPIC its useful in application whe dealing with suspicous vechiles.
http://www.cpic-cipc.ca/English/index.cfm?CFID=515950&CFTOKEN=60459433&jsessionid=1e302920531157504644031Just hit search now and you can do it by lisence plate (make sure the marker is on the correct province) VIN number so if your purchasing a car or Bycyle serial numbers, no I am not kidding.
Oh and for your enjoyment a youtube video on the BC system ALPR (Automatic Lisence Plate Recognition):
http://www.youtube.com/v/U_ad5Jaa0LA&rel=1