It really isn't just that most of us are lazy (believe me we are) its that we don't have real alternatives. Being locked in a two party system, both of which are bought and paid for by corporate interests, means we fundamentally have 0 choice. Sure they differ on social wedge issues (gay marriage, immigration, abortion, gun control etc) but when it comes to foreign policy, corporate money in politics, the patriot act, Guantanamo, selling arms to US sponsored terrorists, etc they are all exactly the same. We elected Obama because he promised us change. What did he give us? More of the same old bullshit.
We got fed up with it and responded with The occupy movement, how did they react? by kicking us out and ignoring us. Rinse wash repeat and fuck the general populace.
When your entire government is bought and paid for by the 1% writing letters and calling your congressmen is pretty much useless.