Night, for instance. People who live with street lighting find it hard to understand how dangerous it was at night, with everything from breaking your night to freezing to death because you lost your way -- and how carrying a light was an invitation to robbers. It was so drastic that many legal systems distinguished between crimes committed during the day and those at night. (Or to be more precise after and until civil twilight, when things can no longer be clearly seen).
Or the sea. In Hinduism, you lose your varna status by crossing the sea. And we have a classical Greek speech where a man is defending himself against a charge of murder, and one thing he brings up in his defense is that he went on a sea voyage and arrived safely, when everyone knows that murderers imperil themselves and everyone else on board.
Crossroads are another. I learned quite a bit about the folklore -- Hecate, goddess of the crossroads (among other things); burying suicides at them, etc. etc. -- before someone pointed out the obvious problem that if you arrived at a crossroads in the forest and took the wrong one, disaster or death could easily follow. Not an easy notion to convey to someone used to good maps and road signs, let alone GPS.