You were quite right (and I was delighted) to make the distinction between stereo pairs and a 2D projection of one. True stereo viewing demands the point of view of adjoining images to be widely separated, a geometry which can be achieved by photos taken from widely different locations and then merged to form a photogrammetric model. This is not what you would see if flying over a landscape where the only actual separation is the 2 or so inches between your eyes.

Still, the illusion of stereoscopic vision can be created by perspective and foreshortening, as it can be experienced by flying a light plane through mountain valleys or cloudscapes. I hate to be nitpicky, but I spent five very long years of my life doing this professionally as an air photo mapper, and it is such a treat to find someone who actually comprehends the distinction.