system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the legalities for private companies to hire people to drive around cities with LPR (License Plate Recognition) readers, which scan every car that goes by, and report cars that are 'flagged' to recollection, police, etc?
gpt
I did a ride along with police in Arizona a few years ago, they already had cameras on their police vehicles that automatically scanned every license plate and flagged vehicles driving around them so they could pull them over. 

I don't know about the legalities, but that technology has already existed for years.