The key point of what we should say is hidden in this paragraph: The
systems everyone is talking about are about plausibility checking.
Actually ensuring accurate information would involve *using* the
address data to complete some step in the registration process. Like
what the one "survey" respondent told you: Send in a form that must
be sent back with a signature before the registrant can proceed. (Or
cancel the domain name if the form doesn't come back after some
days.) That method isn't practicable for registrars with an
international client base, either.