I think there are several reason.
- Al-Qaeda is and always has been a fairly formiddable terror network, but I think their power is overestimated or misunderstood by most Americans.
Al-Qaeda has always tended to operate more heavily in the Eastern Hemisphere. They have tended to operate most heavily in regions where Islamic terrorism has the most support amongst the citizenry.
So eventhough they have (a now diminished) impressive global financing operation they do have distinct limitations and reservations when it comes to attacks. It is vastly easier for them to run ops in the Middle East or North Africa than it is in Europe. However due to the large (proportionally) Muslim populations in Europe these days they DO have some inroads that they can make into the European continent, and that is one reason Al-Qaeda has been able to strike Europe more frequently than it has struck North America.
And plus, their money is mostly in the Eastern Hemisphere, it is easier for them to move money into Europe for ops than it is for them to get it in to the United State.
One thing the United States does seem to have an advantage in over Europe is financial accounting and money tracking. The Enron scandal was economically huge, larger than any commercial scandal I can think of in Europe. But overall it was fairly small potatoes and it was achieved via tricking out the system, and the system became even more stringent after that.
Look to Italy and the Parmalat scandal though and you see a scandal that is much more serious than Enron because it shows evidence of a financial accounting system that is basically powerless to stop complete lies and distortion on a total scale by corporations.
While Parmalat (I don’t think, I’m sure they were larger as a proportion of GDP though) was not as large a company as Enron, the things they did were much more deceptive and underhanded, and they were things that Enron couldn’t have gotten away with in the United States even with AA’s help.
- It takes a lot to really classify itself as “huge” attack in America. I mean, this is the country with dozens of serial killers, spree killers, school shootings, et cetra every decade.
Things like car bombings, minor hostage takings, small-scale conventional attacks et cetra do not affect the American psyche in a hugely significant manner because they are so quickly overwhelmed by the media rush.
I think Al-Qaeda knows this so they prefer to only attack the United States in ways that guarantee to be huge to American morale.
The destruction of the World Trade Center is something that does that (they failed it once.) And a sinking of a U.S. Naval Destroyer is also a very big thing, but they couldn’t achieve that.
They tried a few things before 9/11 that did not work to the degree they wanted it to, so the hijacked planes were definitely a “Plan B” sort of thing. And even if American planes can still be hijacked in the same manner, the U.S. is much more willing, ready, and able to shoot such commerical planes down now. So the destruction will be difficult to reproduce.
Al-Qaeda has to develop a plan that will actually 1) hurt American morale, 2) be huge in scale and 3) have a decent chance of success, before they can even start implementing it. And I wouldn’t be surprised if they haven’t even been able to plan anything effectively.