already told you why
The Vanishing of Ethan Carter looks as good as it does. But as impressive as their photogrammetry looks in still pictures, it's the raw scans that really show how absurdly realistic the method can be. As proof, you need to see, admire and play with the collection of scanned 3D models released by dev team The Astronauts and embedded below. I guarantee it contains the sexiest moss you'll see all day.
check out this in-depth dev blog
by The Astronaut's Andrzej Poznanski. In it, he says things like "speaking of quality – these are raw unprocessed scans, and some of them are actually lower res than what we have in the game." Blimey.