In an environment where police officers are effectively immune from any consequences of any actions, which appears to be almost true - barring widespread media coverage and consistent pressure from essentially a majority of US adults for multiple months at a time - the actual nature of the pretense used to take the officer's word for things is pretty immaterial
The theory-practice gap is so wide as to make the theoretical maxima essentially fantasy with body cameras that are proprietary and owned and operated by the same police departments they are supposed to be an accountability mechanism for
In theory you could, but that requires something like a small scale mass spectrometer to feed recordings into the camera log. So in practice, not realistic... yet.
