The claim that the horizon is always at eye level, is a fundamental basis for flat earth perspective and reasoning, yet I have never seen any flat earther prove this claim.
I've seen flat earthers point the camera at the horizon and move the camera up/down to show that the horizon seems to follow the cameras level, but never seen a flat earther show and prove that the horizon is at eye level at higher altitudes.
So my questions:
Has it ever been proven?
Would it not be easy to prove this claim?