This link explains why. If a city goes to the expense of a body cam program, after having reached a policy decision to go that way, there is simply no excuse for non-use. It is criminal that a woman was killed by a cop without any body cam record of the encounter in a city with bady cam usage required. If the cops can get away with this, why have the program? Put teeth into it. Make non-use in citizen encounters a felony, and let the courts deal with suggestions of extenuating circumstances or exculpatory factors. If body cams are issued or used on any shift in non-working condition the person responsible for quality assurance should have no job security beyond recourse to the courts. Any bargaining unit contract interfering with or compromising protecting the public via body cams should be held void as against public policy. No employer-union can, for cops, bargain away protection of the public from rouge or criminally stupid (aka grossly negligent) police actions. You issue a badge and firearm and powers, you have to keep reasonable checks and balances. The public deserves no less.
There is NO EXCUSE.
UPDATE: Even while buying a cup of coffee while on shift, the camera should be activated and recording the encounter. NO EXCEPTIONS.