Why are American citizens poorly informed?

Based on the essay of Michael X. Delli Carpini, we understand that the citizens have a lack of knowledge about politics - even if it is not uniformed among all the population. But we can go further by using this essay to question why are the American citizens poorly informed.
On the one hand, we can say that Americans may not be interested in politics because the political structure is sometimes hard to understand. In his essay, Michael X. Delli Carpini wrote "the American political system is an enigma. [...] It allows almost unlimited participation while doing nothing to facilitate it" (Caprini, p.152). The complexity of the institutions and how they work may be one of the reasons why the task of the citizens -getting informed about politics- is not facilitated.
On the other hand, we can consider that the lack of interest of Americans in politics is due in part to the politicians themselves. Indeed, in the light of what Kuklinski and Quirk are saying, politicians use rethoric in order to convince the voters. That may be the reason why Americans don't think they have to focus on serious knowledge, because they are not educated by the politicians to do so. But this information can be discussed. The relationship between politicians and citizens is a vicious circle: politicians have to use rhetoric because some citizens don't focus on their ideology, but by using this rhetoric, they are not going to push the citizens to improve their knowledge about politics.

Today, many citizens and scholars are blaming the media and citizens for focussing on the image of the politicians rather than on their speech, and therefore decreasing the integrity of the political debate. As an example, Delli Caprini said that "the single most commonly known thing about George Bush's opinion while he was president was that he hated broccoli" (Caprini p.134). Maybe we can use the same thought process: we may not have to blame the citizens and the media for focusing on less serious concerns about politics, but rather blaming the politicians -and their communication advisers- for their use of the image in order to attract the voters. This may lead again to a lack of interest in the political knowledge.