They can. But theres a reasonable level of trust that a security feed has been kept secure and not tampered with by the owner if he doesnt have a motive. But what if not even the owner know that somewhere in their tech chain, maybe the camera, maybe the screen, maybe the storage device, maybe all 3, the image was "improved". No evidence of tampering. We'll have the police blaming Count Rugen for a bank robbery he didnt do, but the camera clearly shows a six fingered man!