So, the answer to your last question is "yes", same as with any other camera.
a) Discover the camera was a dummy;
b) It was out of service at the time of the incident;
c) The camera is a live stream only and does not record footage;
c) The owner is unwilling to pore over hours of footage to help you;
d) They find an image but the quality is insufficient to identify a person or a vehicle;
e) They find a satisfactory image but are unable to share it with you for data protection reasons.
So, the answer to your last question is "yes", same as with any other camera.