Did you mean that his eyesight is not good enough to detect it, but that yours is? Or, did you mean that no one has good enough eyesight to see it?
If no one has good enough eyesight to see it, the photo can hardly be properly said to be demonstrating or illustrating 'curved earth'.
You are avoiding the issue.
Just exactly how wide must the field of view be for curvature to be detectable by the human eye?
Again:
Since the curvature would be seen at the horizon, how far from the horizon would someone be at 35,000 feet to see curvature?
If passengers can only see a very small segment of the curve, how do they know it is a curve?
If the human eye can detect curvature in such a small field of view, why can the human eye not see a much greater curve over a much wider field of view a lot closer to the ground? (i.e. - on a beach looking out at a 150-180 degree wide field of view - from as far as you can see to the left to as far as you can see to the right - a very long continuous ocean/horizon line)
How/Why is it that a person on an airplane looking at the horizon with a comparatively narrow field of view can see curvature while the same person on the ground looking the horizon with a comparatively wide field of view cannot?
If a person were situated in the middle of the Pacific ocean - where nothing but ocean can be seen all the way to the horizon for 360 degrees about that position - maximum field of view - would they see curvature?
No, of course not - all they would see is the horizon - at eye-level - for 360 degrees about them.
If the side-to-side horizontal field-of-view distance is
far more (
especially if it is a continuous 360 degrees
) than the proposed distance from the person to the horizon - why do you not see side-to-side horizontal curvature?????
For example, if you claim that there is significant curvature between you and a ship on the ocean that is - say - 6 miles away -
do you not realize that if the side-to-side horizontal field-of-view is greater than that - especially, much greater than that - you would see significant side-to-side horizontal curvature?????
The same amount of curvature between you and the ship would exist in the side-to-side horizontal direction also.
Do you not realize this?????