Regardless of whether some of the time, a police department is full of bad apples and concealing or destroying body-cam footage, if you treat your body cams as a backup -- and only look at it when something goes wrong -- you're going to discover that your body cams weren't working all along and no one noticed.
And then you're going to look hella guilty of hiding evidence, even if it was just bad IT policies & procedures.
If you have body cameras, you need a process where you frequently, randomly pull the footage from random officers, and check whether it was turned on, recording properly, filed correctly, whether the camera quality is uselessly grainy, etc etc etc.
Otherwise, just like you don't have backups if you aren't testing your restore process, you'll find out you don't have body camera footage even when it would clear you of blame.