What are all the other countries organized on. Happenstance?
I like our idea better than others, but Monarchy is an idea. Communism/socialism is an idea, Dictatorship is an idea. Theocracy is an idea. Might makes right is an idea. Facism is an idea. Feudalism is an idea.
For whatever reason, there is a common liberal view, that America is flawed for allegedly not living up to our highest ideals. Liberal after liberal have been issued these talking points, and spew those lines in many speeches and talks, on many subjects.