i remember being on a jury in a case that involved child abduction, the police did not record the interviews they conducted with the child after it had been rescued. i talked to the prosecutor afterwards about it and they said it's to easy over analyze every word said and twist it to appear as something else. to easy for a defence to say they were leading the witness and therefore the recording should be thrown out. remember there was video of the Rodney King beating. the defendants slowed it down and pointed out on each frame actions that King supposedly did that were threatening to the officers beating him.
recording everything is not a panacea. not having everything recorded a sign of nefarious actions.
This amounts to the "you can't handle the truth!" argument. It may be true that the average citizen, and thus the average jury member, is unaware of what ethically-conducted police work looks like. But that doesn't seem to constitute an argument that keeping everyone in the dark about what average police work looks like is an overall good thing.
recording everything is not a panacea. not having everything recorded a sign of nefarious actions.