a writes:

which is true enough IF ONE IS STATIONARY. If one is moving distance
and depth estimations are actually pretty easy.

If they were easy, then a lot less time would be spent in pilot training
warning pilots about how deceptive visual cues can be, and a lot less time
would be spent teaching various clever ways to try to estimate distances.

Even golfers can
estimate to within a fractional club (that would be about 10 or 15
feet) at distances out to two hundred yards or so, and pilots with
suitable experience see their landscape unfolding in what amounts to
three D. Fly over a mountain ridge then a valley and claim it's not
seen as 3D.

It's not seen as 3D. As I've said, depth perception only works to up to 100
feet or so. The rest depends on visual cues that may or may not be accurate.
Pilots who have misinterpreted the cues have regularly crashed and died.