When I choose to photograph in black and white it isn't out of a sense of nostalgia but because I want the abstraction that comes from reducing things to shades of grey. Given that any photograph or painting portrays only what it does and not the rest of the world it is at best an edited or constructed truth. I guess you could think about NASA or spy plane images as the ultimate truth showing all of the world in an objective way. So I think most people accept that there are degrees of transparency in photography.
As to a hierarchy in visual images I think that this has been true in the public mind, that photography has been thought of as an accurate depiction of reality. The use of photography as a tool in the hands of NASA etc has given people a sense of the documentary value of photography.
The example of the photo vs identikit in court is a moot one because you would probably have to identify a suspect from a line up. Your memory would likely be much better accepted than either image.
As digital photography and image editing matures I still think people will still accept the photos they take as a true representation of their memories but are likely to become increasingly cynical about the truth contained in images in the public domain.
For people who aspire to make art I think reality is a choice. Many of the photographs I most admire involve some departure from reality.