I think this is the number one reason for UFOs being judged as aliens or even as flying objects at all. People don't realize that that if you have no idea of the distance, size or speed, then you can't even attempt to estimate any of them and seemingly impossible things happen. Planets look like balloons, cars look like stars, etc. This seems to be the problem with those military pilot's videos and accounts.

Whenever someone says it was "as big as a ..." or "impossibly fast", they're usually interpreting what they actually saw through their faulty intuition about those things. Angular size like the OP said is a useful observation, but not actual size.

I experienced this the first time I flew on a plane. I was watching the clouds passing by just below the plane and had a feeling for our comfortable speed, then suddenly a whispy bit of cloud in the foreground shot past much faster than I thought we were travelling and gave me a little shock. I then realized the clouds I'd been watching were probably much further away than I'd imagined.

I don't think those papers mean what you think they mean. I could be wrong, I'm not perception studies expert, but the first one seems to say that binocular parallax (signals from looking with two eyes) are relatively reliable, especially in daylight conditions (the case you critique). Second two seems to talk about how high up in the sky something is as being the biggest distortion in estimating distance. Also the last one involved bizarre artificial conditions of looking through light bending prisms. Our eyes are definitely unreliable (to a certain extent), you have a blindspot in the middle of your vision in both eyes (retinal optic nerve spot) but you nearly never see it because your brain can interpolate. But I think judging something like this, in the well lit conditions described, I think you're exaggerating the difficulty. And I dislike that because it seems dishonest, and cruel to witnesses. It's a form of gaslighting. You have people (Navy pilots, civilians) coming forward and seeing things, and then everyone else wants to say, "Are you sure you saw that?" I get it, because you didn't see it, so it's natural to doubt. But you will walk across the street today, and reach down and pick up a coin, and I'll stop you and say, are you sure those cars are that far away, are you sure you see the coin. Don't cross the street, don't touch that coin. Maybe it's a hallucination. Maybe it's a bomb. Maybe it's a snake. Of course I wouldn't do that. That would be crazy. People casting doubt should doubt their own doubt too. It shouldn't be natural to doubt when so many people say the same thing.

It was behind some trees about 30-40 meters away, I ran across the street to get a better view(it was suspicious after all) and didn't notice much parallax shift, but I doubt I would have seen much against a blue sky. Obviously if you don't have a good view of a random object like that it's extremely hard to judge distance. It might as well have been a point object that's almost impossible to judge anything other than color/shape/movement. The movement is what made me realize it's a UFO, if it disappeared or kept moving at a reasonable rate I wouldn't have though twice about it since it's probably some white/silver balloon being blown in the wind or something.

Even if it was close by, you don't jump from almost stationary to the other side of the sky from your perspective at a reasonable speed.