"it is generally true that any monster or man can see in total darkness as far as the dungeons are concerned except player characters."
From the little green book, Monsters & Treasure, Gygax and Arneson (c) 1974. The era generally considered "pre-1e" by modern archaeologists. Why do I think it's Awesome?
This rule intelligently simplifies. Want your human bandits to surprise out of the darkness? OK go for it. Want your human bandits to be spottable from a distance due to their torch? OK go for it. The referee has, by rule, complete flexibility without any of the guilt or complications that more modern editions bring.
Just make the story fun, and assume there was "some explanation" that was as workable as it was irrelevant.