Individuals attempting to make a complaint would now be informed that the incident was caught on camera. False complaints are likely dropped outright at that point.
After wearing cameras, police then stopped wearing them but complaints continues to be low even when there were no cameras.
The likely explination is that the police's behavior had changed and continued in the changed state after the camera was removed.
The behavior of newly detained suspects, those detained after body cameras were removed and so without experience of the body cameras in the past, could not have been changed by an experiment they had no part in nor knowledge of. Thus false complaints would continue at the same rate.
Individuals attempting to make a complaint would now be informed that the incident was caught on camera. False complaints are likely dropped outright at that point.