The chink in the armour
The problem with these systems which is what the civil liberties is heading towards with their statement is that the lack of data around useage is due largely in part to the systems the store the footage have no formal governance built into them.
Most public sector organisations struggle with governance on an IT system at the best of times which is why you need an IT system to enforce it on the staff using it. These systems have some basics like expiration periods (e.g. footage is deleted after 30 days unless tagged for evidence), but they don't capture other data like checking out a file for use or if it is being used for evidence attaching something like a case number or reference as metadata. Simple additional fields of data attached to a workflow would help build and enforce governance from a systems point of view.
Obviously you then have the argument of blaming the software makers/camera providers for not building this into their software. They would then turn round and say that it wasn't a specification the customer asked for and we're back to the earlier part of my comment.