Americans are no more or less stupid than any of their European counterparts, actually we are you.
What is stupid , or actually an anachronism, is the polarization of the two party political system that does not allow for real change.
Most of these politicians are not stupid. You do not get to play at that level by being stupid.
They know what need to be done, but are unable to do so and survive with in the political environment they belong.
This holds true for Republicans and Democrats.