The (gamepedia) wiki claims that "every enemy" has a chance of dropping a dungeon key for the biome that it is in, and I see nothing to suggest otherwise in the other wiki or update logs, yet it seems strange that all farming tutorials for the keys are making use of spike traps and meteor heads rather than statues hooked up to a timer.
If it were the case that statues could spawn mobs that could drop keys then I'd imagine people would be making massive statue farms for insane rates rather than an unexpandable meteor head farm. Or is there perhaps some reason why this method would be slower or wouldn't work?
Was it confirmed by somebody that statue summoned mobs can't drop hardmode keys, or was it just assumed to be the case? Is it true?
Edit: (For bounty I'd rather the answer to show the code or an official dev statement, not from the wiki, it appears that the wiki has now changed its statement)