Some of it is genuine indoctrination into civic religion. When Americans first learn about democracy and the Bill of Rights and all that in the abstract sense, of course they sound good! Of course those values make sense in a vacuum! Then they're taught that the British were the opposite of this and our boys (who you see everywhere, who your school might even be named for) were on the right side. They may never do more than a superficial dig into the actual functioning of the federal government (much less state and local governments, much less the long history of all of these) for the rest of their lives. At my American high school -- which was a good public school, where almost everyone graduated and most went on to further education -- we frequently did nothing but crosswords in Government class!

The real test is how much they dig in when challenged on just how good the Founding Fathers actually were.