agreed - that was a bad choice for an example. Maybe these old examples here here tell a better story.
And you are right - once you scan your footage perfectly, you discover how much film grain is present in dark areas. It has a much higher amplitude and size, compared to normally exposed areas. Here again you can find two positions: some say “grain is the film” and leave it in the footage, some try to get rid of the film grain in order to recover small image details which would be not be noticeable otherwise (I’m in this party).