Or take the debate we had on 9/11 conspiracy theories. Some people thought that unexplained and otherwise suspicious things in the official account had to mean that it was a government conspiracy. Others considered their prior for "the government is ready to conduct massively risky operations that kill thousands of its own citizens as a publicity stunt", judged that to be overwhelmingly unlikely, and thought it far more probable that something else caused the suspicious things.

Don't forget the prior: "The official account of big conflicts with a lot of different interests involved will always leave some things unexplained or otherwise suspicious." "Government agencies who fail on a massive scale don't like to be transparent about how the failure happened."

Actors in government agencies didn't think: "How can I convince that public that 9/11 wasn't an inside job." They think: "How can I influence the public perception of 9/11 in a way that my department gets more funding." Or when it comes to president Bush at that time: "How can I influence the public perception in a way that makes it more likely that I'll win the next election."

Newspaper journalists don't care about fact checking every single fact in their articles. It's way to much effort. If you have background knowledge you will in most news stories facts that aren't true.