Why do people ID photos?

Why do people ID photos? Photo identification may be used for face-to-face authentication of identity of a party who either is personally unknown to the person in authority or because that person does not have access to a file, a directory, a registry or an information service that contains or that can render a photograph of somebody on

Photo identification may be used for face-to-face authentication of identity of a party who either is personally unknown to the person in authority or because that person does not have access to a file, a directory, a registry or an information service that contains or that can render a photograph of somebody on