I'm not sure that was the case in 1947. I think attitudes were a whole lot different. I suspect that had FDR survived, he'd have had a good shot at winning in '48, and the whole nation had just rallied around the US Government for WWII. I don't think that an inherent "mistrust of government" would be a given, or even a reliable variable for the basis of a PSYOP campaign at that time.
Maybe mistrust was too harsh. Skepticism perhaps? A general show me before I believe? You have to admit the general psychology is sound. If you are skeptical about a general subject, and I play to that by making it seem like I’m hiding something when I’m really not, Basically I’m hiding in plain sight. And when I couple that with giving you something that fires the imagination, I’m giving you what you want to believe. When you think about it, it’s a mind screw twofer.