i think that's more of a case of people putting trust in their government rather than "if it's on paper it must be true." otherwise i'd write "i have $3 billion" on a piece of paper and be one of the happiest people alive.
anyway, if everyone believed what was written on paper we wouldn't be on this forum talking about how not true it is. the people who believe it because it's on paper would probably believe it even if it wasn't; writing it on paper might've been in excess of the "proof" required to win them over.

