How much do ordinary people know about Batman? In a world full of super powers, cyborgs, time travellers, magic and aliens, do they know they know that Batman is a mere mortal in a costume? Would they think he has super powers? Maybe they think that he actually IS a bat, like Kirk Langstrom.
What about his allies and enemies? Do the Riddler, Penguin, and Two-Face know he’s just human? How about Jim Gordon and Harvey Bullock? How about other superheroes? Close friends know, but what about Guy Gardner, for instance?