I don’t understand the point about presuming innocence. These are cases where it has been determined that a police officer has shot someone. Not cases where somebody was shot whilst police were nearby and we don’t know who did it, which would be “police involved shootings”.
Although I don't read clearly that the police were the ones that pulled the trigger. And "police involved shootings" doesn't say anything other than there was a shooting and an officer was involved. So the media does dance around the details.
Maybe it's cop-speak, maybe it's liability protection, maybe it's to get the readers to be curious on the details or a combination of all. I don't know.
"Officer was shot" or "officer-initiated shooting" is more clear.