Further, the challenge is not completely autonomous bots that are somehow separate of humans, never has been, all code on Earth has and will have a human imprint even in the wildest AGI fantasies. The first false dichotomy is anonymity and veracity, the second false dichotomy is human and bot. And tho biggest challenge comes from a specific human-bot combination, the Cory Doctorow Reverse Centaur (though Centaurs also complicate things). One human can suddenly impact the "volume" of discourse, like a magic hidden megaphone that somehow no one can detect at a dinner party where the lights are too low to see who is talking. /And/ if there's a door check at the party, it's easy to transport someone who makes pennies a day to show up at the door, look like anyone you want, and then come inside with a magic hidden microphone that you provide them.
I think it's less about proving human, more about proving /reputation associated with an entity/. It's not about whether "awbvious" is human, but whether "awbvious" is committed to acting human. Committed to not use a hidden, magic megaphone. Committed to not using hidden, magic megaphones with others. Which I am.