It matters greatly to most people whether a scene in a photo existed or not.Alan,
That pre-supposes that people care about what is being depicted in photographs. They do when it comes to family shots and a few other things, but otherwise they care about how the photograph looks.
For most people, how the photograph got to look that way doesn't matter. For some of those interested in photography, the method and materials matter.
Method and materials seems to matter more for prints or projected slides than images viewed on a screen, but again, only for some.
Whether that is instinctually understood, implicitly or directly is another story.
How they can be sure that they are not getting duped, is only just dawning fully on most people.
Also there is no inherent basic or natural understanding of photos.
Show rain forrest indians who are not used to looking at photos a photo, and you will discover a whole spectrum or world of ways in which an image can be misunderstood and not understood it all.
Anthropologists did that decades ago.
Our grokking of photos, depends on a vast network and cloud of social and cultural knowledge and ballast, that is gradually and invisibly fed to us piecemeal through our whole life.
And that includes stuff that would seemingly be details to even the most hardened cultural barbarian, like grain, MTF curve, and highlight response.
These are signifiers of real emotional fulcrums, and not just masturbatory points on a spec sheet.