I'm not saying it's a system that's in place. :p
Because, youre right, it's not.
It's more of an honor system kinda thing.
But even so, if you vouch for an account and the account isn't anything like what you vouched it to be... people will still be upset with you for saying so. It's kinda similar in that way I suppose. But I agree, it's not an "official" kinda thing.