Although your point about earth isn't completely true (night lights are very visible from space and we don't have photos from before space missions), the thing

Although your point about earth isn't completely true (night lights are very visible from space and we don't have photos from before space missions), the thing that concerns me is whether mining Helium 3 from the moon will affect the terrain's reflectivity. Helium 3 will simply be scooped off of the surface and while only small amounts of it are needed I don't exactly know how little will the impact on the moon be. Remember that the moon is many times smaller than earth so the comparison is apples and oranges.