I'm still surprised there's so little blowback to the idea of police recording everything that goes on around them, including (perhaps?) in public restrooms.
Hmm... why should there be? After all, part of the reason they're getting the cams is to fight police corruption, right?
That being said, the recordings said cams make are
evidence. I'd view it a bit like videotaping a surgery or something. You store 'everything' for the mandated period of time, if a public information request comes in you chop out the irrelevant stuff, and you store the relevant stuff(IE involved in a case) for as long as necessary. Bits good for historical or training purposes are kept indefinitely.