That checks out with my experience. I don't think it's just reading either. Even deeper than stranger danger, we're inclined to assume other humans communicating with us are part of our tribe, on our side, and not trying to deceive us. Deception, and our defenses against deception, are a secondary phenomenon. It's the same reason that jokes like "the word 'gullible' is written in the ceiling", gesturing to wipe your face at someone with a clean face, etc, all work by default.