ExactlyBecause it's called line of sight and there's enough experimentation here on Earth to tell you that the Sun is bigger than the Moon.
Put a 100 ft cube 200 ft from you. Now put a 40000 ft cube 80000 ft from you. I bet if you look directly at that 100 ft cube, you won't see the 40000 ft cube behind it.
You can do this experiment with any small and large object from decent distances. Even a thermos and a vase.
Because. You know. Science.
You have no proof that the sun is 400x the distance and 400x the size besides the BELIEF that you were given by an authority figure
And it doesn't really even matter anyway because the math works out the EXACT SAME for either case
One case just makes more sense while the other case is steeped in religious "science fiction"