Seriously, it's like the default setting of most normies is set to maximum trust. They just read something and immediately trust it. They are told something and they simply trust it. Just like that! Does not matter what exactly it is or how absurd or unbelievable it is. If said information comes from some percieved authority, they'll simply trust it!
Sure, after a while they might start to question some things, but the very default is immediate trust.
Other huge problem is the inability of masses to comprehend complex concepts. You can put all the information right in front of them and they still won't be able to understand anything. Even if they start to understand something, usually they revert back to fallback questions like: who are they, why would they do it, it's not possible for everyone to be in on it or - at the very least - it's simply not possible, because that can't be true.
Who needs censorship when the masses are so dumbed down and their thought processes are so inert that even given all the information sitting right in front of them they still seem to be completely unable to get it?
I would suggest that the ultimate cause is more subtle and thus easily misinterpreted. It has to do with the true nature of human consciousness, but for purposes of discussion can be formulated roughly as, "How do people determine what Reality is?"
The first observation should be that we do not all do it the same way. The unstated idea that we all do it the same way--the only difference being that some do it well and others poorly--is totally incorrect and should be consciously rejected.
To be brief and put it in very primitive terms, what makes "normies" "normies" is their in-built way of deciding what Reality is, and generally it is from those they consider "authorities".
This mechanism can overwhelm even first-hand experience. All reasoning and even facts will give way to it. With close attention to their "reasoning", they will often invent "facts" outright to support their views. To be more precise, they begin with their conclusion and reason backwards to necessary facts.
I've seen it here plenty. I think many of us have.
Yes, blind trust in authority and not looking closely into anything seems to be their default mode of reasoning. Or in other words: it's not that they can't, it's that they simply won't look closer into things. They have been conditioned to trust and that's what they're doing even while staring right into the face of completely contradictory information.
Well, I specifically posted to point out that they can't, and not that they they won't, and I find insisting on it otherwise to be erroneous and counterproductive. But everyone is free to believe what they choose, and they freely choose they do. I have also found arguing about it to be entirely pointless, which is another thing I learned about how people actually think.
But on the extreme outside chance anyone reading this actually wishes to research the idea further, a psychologist named Julian Jaynes came up with a key insight regarding it almost half a century ago. His work was just a small part of the overall picture and he got important parts wrong, but it's close enough to lead to the next step.
A decent description of his idea (again, incomplete, flawed and out of context) is in the wiki on what he termed bicameral mentality:
That does explain a bit why some grown and seemingly intelligent adults still believe in jewish desert fairy tales from men in dresses and robes…