the other half from what people erroneously call the "dark" side
While there can be no doubt that some section of the populace erroneously call it the dark side we can only hope that their number is small. The rest of us call it the dark side metaphorically. Nobody (excepting perhaps that same section of the populace) is suggesting for a moment that the Dark Ages were literally dark or that the Dark Web is literally dark. We use "dark" as a metaphor for things which are or were unknown.
That said, there's nothing wrong for non-astronauts referring to it as the far side of the moon instead.