A couple years ago I remember reading about something called the "CSI effect" or "CSI syndome". Prosecutors in criminal cases have trouble with juries which have watched TV shows like CSI and believe that the show accurately reflects police forensic practice. Juries have questioned the lack of DNA or other detailed forensic evidence which police departments often do not gather. This is partly because real police departments have limited budgets (probably smaller than the TV show's budget) and partly because TV shows routinely stretch the truth -- sorry, the police can't run compuerized facial recognition on a witness drawing and get a unique hit on a suspect.
I just started reading the book Among the Truthers by Jonathan Kay. The book is a description of consipiracy theorists in the United States including 9/11 Truthers, Obama Birthers, and others. A couple of the 9/11 Truthers he talks about in the first chapter talk about the US government planning and executing, or at least orchestrating, the 9/11 attacks.
It occurs to me that the assumption that the US government (or some group of officials) can pull off such a complex operation without anything leaking needs a name. I suggest "The Mission Impossible Effect", referring to the 1960s TV series (not the recent movies). In each show they create a complex plan involving half a dozen people and precise timing, getting it to come off successfully each time. It seems too many people assume that the US government can really pull off such complex operations with perfect secrecy.
In reality, it takes little research to show instead that government agencies are populated by real human beings, political and bureaucratic infighting, bumbling, and incompetence. The CIA had a hand in a few foreign coups, but couldn't kill Castro. The US government apparently orchestrated 9/11 to take control of Mideast oil but left the followup takeover (the apparent purpose of the Iraq war) to inexperienced political appointees.
I can't say for certain that the US government didn't orchestrate 9/11, but given its track record I find it hard to believe that something which would have taken a lot of people to pull off (from planting explosives in the Twin Towers to the missile it's claimed hit the Pentagon rather than an airplane) could have been executed without anything going wrong. But read enough political thrillers or watch enough Mission Impossbile and it's easy to believe that organizations can plan and execute complex operations without a hitch.