Mountain View’s decision to shut down its automated license plate reader program is a reminder of an uncomfortable truth that surveillance technology is only as trustworthy as the systems—and vendors—behind it.

This week, Police Chief Mike Canfield announced that all Flock Safety ALPR cameras in Mountain View have been turned off, effective immediately. The move pauses the city’s pilot program until the City Council reviews its future at a February 24 meeting.

The decision comes after the police department discovered that hundreds of unauthorized law enforcement agencies had been able to search Mountain View’s license plate camera data for more than a year—without the city’s awareness....