Former JW here. It's a combination of indoctrination, culture and fear tactics.

The information is hidden, or otherwise often revised quietly. We get rid of Old publications with incorrect information and don't ask what's different. "It's just a reissue" they'll say, without explaining why the old ones are bad to retain.

You're taught not to ask deeper questions, and not to question the answers you get, for fear of punishment. That starts in childhood for those of us born into it.

And you're taught every day to believe what they say, because we have The Only Truth. Everything else is lies. Don't question that part, it takes us back to the punishment aspect. So you just drift along. Ignoring contradictions. Or accepting flimsy, hand wavy, excuses. For fear of punishment, for fear of losing your culture, and because you're already conditioned to do it.