Nothing you've said leads me to believe that evidence from a bodycam will be available to exonerate a member of the public in a case where the person wearing the camera is "in the wrong".
In a case where, for example, a bodycam-equipped member of railway staff authorises a passenger to travel on a train where their ticket would not usually be valid and they are later challenged by a different member of staff, a passenger can have no expectation that the exonerating recording will be available to their defence. The expectation is that, if such a recording is requested, it would be "unable" to be found (with the usual excuses; camera wasn't switched on, recording was not retained, clerical error means it was deleted, "data protection" claims, etc. etc.). This sort of thing is exactly what is being seen in many cases internationally involving staff and officials wearing such cameras.
Bodycam evidence will be used to help prosecute a member of the public, but only in exceptional circumstances would it be available to exonerate them. Members of the public should make their own recordings of anything they believe could be necessary as evidence. If staff members refuse to state things "on the record", then clearly you shouldn't trust them "off the record" either.