I think part of the hesitancy of body cams is how do you solve the problem of hours of useless video of them sitting in a car, etc.?
Is it worth it for a municipality to have a body cam going when they hand out a speeding ticket? Or any of the 99% of the boring stuff they do (loud neighbor, minor traffic accident, etc.) That is likely to cause a lot more BS court time. Each $50 device could end up costing taxpayers $1000's if the idea is to record every encounter.
Maybe somehow tie the body cam to start recording on key events: police person exits their vehicle, they start running (gyroscope?) or when they un-holster their weapon (gun or taser), and ability for manual start.
I don't have any expertise but it would be cool to have it just recording to some device in their vehicle, then if they are too far away it records locally and syncs up when they return. Vehicles could be transmitting event data to HQ and live video after an event triggers. This could help with officer safety where an officer might need backup but can't ask for whatever reason.
If a person wants to do something malicious, they just need to cover the camera or make it "malfunction" - its not going to stop that activity.
I think the path to sell this type of thing is officer safety and officer CYA for their own careers. Also for more experienced officers - video of expertly handled encounters could serve as training to recruits on how to handle difficult situations like domestic violence.