There are no reliable studies. There have been multiple demonstrated examples that user data has been shared, and systems have been hacked.
We have plenty of evidence of harm and no good evidence for effectiveness. We don't need to "save police resources" we need more well-trained capable police officers who are doing good police work AND good community work
"Austin spent $1.2 million on Flock cameras. They scanned 113 million license plates and got 165 arrests. That's $7,300 per arrest"