I just watched Disclosure Day and there's a plot thing that I've also seen in one of Dan Brown's The Da Vinci Code where everyone assumes the whole world is going to stop and forever change upon some special news. In Disclosure Day even traffic stops so people can look at their phones and get the news that aliens are real (not really spoiler, given the title).

it seems, idk, infantile?

Many people don't trust the news. Most people don't change their minds easily. People have tons of motivated reasons to disbelieve things right in front of their faces, and all sorts of defense mechanisms against the truth.

It's fiction, so what? Why am I not bothered by Emily Blunt's mind-reading? I guess it bothers me bc this is the part of the fantasy world that's supposed to behave like our world? idk why it stands out to me; I think in general when I can feel an author's craving for some sort of change to projected into their script and unowned, I don't like it. When it's owned, I might not like it either (eg: The Barbie Movie's matriarchy replacing patriarchy), but I respect the self-awareness.