Depth perception is the brain's recognition that, at near distances, the left & right eyes do not receive parallel light rays from the same object. At 2" distance the eyes are crossed! It uses the angular difference to gauge distance = depth.
Luckily, a camera's adjustments show us that at distances beyond 30 feet the light rays are so close to parallel that depth perception is so minimal that it does not matter. After 2 car lengths out one eye or both gives the same information.
For an example of military use of this principle, the WW1 range finders had the eye pieces as normal, then 2 internal pairs of 90° mirrors separate the light path to left & right lenses as much as several feet apart to make the angular difference much larger and useful to get ranges of much greater distances.
