As someone who likes to look into little free libraries in the US while out walking, I'd beg to disagree with the generalization of US book owners - at least what I've seen.
I remember picking up a copy of Rights Talk at a free books book in Montreal, thanks the most political book I’ve seen which I like a lot despite a very dated take on the Americans with Disabilities act (e.g. it is not all controversial the way it was when it was new.). The success of Obamacare also shows that the impasses it predicts don’t necessarily happen in practice although certain “culture war” topics are as pathological as ever.