I only have adult conversations with adults ^^
Back to the kiddy table for you.
Might seem far fetched but why can't they turn it in when called to a scene? Though I can understand this may not be the first thing on their mind. Nonetheless, something needs to be done. I personally don't think they want to wear a camera because they don't want to be held responsible for their abuse of power.
The ability to turn it on, on demand, is more reasonable; but citing their failure to begin recording as de facto dubious behavior is unreal. Especially in a case like this.
Yes his bodycam was on, I am leaning more towards the fact the initial contact was very calm and what happened almost completely unexpected. A routine call in regards to a domestic disturbance (husbands and wifes having a heated VERBAL ONLY debate often yields a police response), and look how it ended. Something a lot of cops (I would imagine) would take no special thought or consideration due to the common nature of the call. "Business as usual".
Another thing to note in aforementioned video is one of the reasons people get shot when they make moves suggestive of assaultive behavior and/or possession of a weapon.
Alot of the time the suspect DOES have a weapon. Clearly.