I've been noodling again on what a photograph actually does and have a new analogy to try out on you all.
A photo, by its indexical nature, or the fact that it looks very very real, or whatever the hell, evokes its subject in a particularly photographic way. I have been thinking of this in terms of it metaphorically bringing the subject to you. The metaphor of the window gets dragged out, and I think not just by me.
What if, instead, we imagine that the photograph brings you to the object?
Without, of course, all the usual trappings of the teleporter as a science fiction device. You're not actually in the war zone, you're not in danger, you have no concerns about how you're going to get home. But the mental gymnastics you perform perhaps make more sense if you treat it as you going there, rather than the subject coming here.
When you see a fashion photo, a model in a dress, a greyhound at her feet, you are not looking through a window at her. The greyhound and dress and woman are not brought to you. Rather, you are transported there, to revel for a moment in that life, to try that dreamworld on for a moment. If you like it, you might buy the dress.
This also matches the documentary photograph. Because you are there, you seek to fill in the surrounding world. If you were merely peering at it through a window, there is no particular motivation beyond an abstract desire to work out a larger sense of "what's going on?" When some MFA student inflicts a documentary photograph of nothing on you, you are like Scrooge transported by the Ghost of Sept 24, 1817, When Nothing Much Happened, to some random empty lot. You struggle to work out why you're here, but unlike the other ghosts, this one offers nothing but a shrug and a yawn. No wonder Dickens left that one out.
I can't actually see why a photo would "take you there" rather than "bring it here" and indeed, the latter seems simpler, easier, and more obvious. I think, though, that the former more closely matches the kinds of effects that photos have on me, and (apparently) on others. The effect seems, in practice, more like passing through the mirror (however lightly) than merely gazing at Wonderland.