Boy did this thread suddenly gain a lot of posts . . .
Just to clarify a term, "deceptively stupid" might better be considered something like "crazy like a fox". Rope-a-dop would be more equivalent, but I can't think of it in a way to describe personality.
Americans often come off as dumber than they are. Part of this is the national chracter -- it is unbecoming as an American to come off as too smart, even if you can completely back it up, teleport by blinking your eyes, and solve advanced fluid dynamics equations in your head.
Part of it is the incredibly limited education Americans school turn out. Most Americans have no glimmer of an idea about more than their chosen skill set.
This is just a characteristic of a highly corporatized industrial culture. Guys in the widget factory don't need to know what is going on in the wutzit factory.
There's a whole list of things Americans could never tell you that are, IMO, things you should know . . . how many cylinders are there in your car's motor? What MHz freq and model is your computer's processor? What is the role your current altitude plays in cooking times? Most cannot even tell you the voltage of their electrical outlets.
There is an argument whether this is bad (economically). After all, if ignorant people screw up their possessions, they will acquire more.
America's character is shaped pretty heavily around the need to know. Computer guys don't need to know what the political guys are doing, nor do the mechanics, doctors, horticulturalists, lumber handlers, crack dealers, or teachers need to know the nature of each others' professions.
Ironically, what you end up with is a sort of occilating model of efficiency.
In its best forms, this approach works very, very well. Look at US industry during wartimes. Everyone shuts up and does their jobs.
At its worst, it becomes a method of hiding failures. You get companies with financial guys making or cancelling IT orders without knowing why they were placed to start with. You get businesses that hire unnecessary personnel, and then fire useful ones because they don't understand which ones actually do what. And, in the end, it will be blamed on the accountants (despite the fact "better" men signed the stuff, not them).
Any system is prone to this. Look at the Soviets! By the end of communism in Russia, their whole system was so screwed up that nothing got done.
If nothing else can ever be said for Americans, they will, given time, get anything done. Sure, it may look like hell, but it will be done.
We can't stop here! This is bat country!