USA has a smaller government than western Europe for sure, but compared internationally the government is rather large (41% of GDP government expenditure, western Europe has around 50-60%, developing countries usually around 15-25%). And I'd argue that fundamental problems of the US economy and society are the results of too little government intervention (inequality, education, especially college tuition and resulting loan problems, health care (partially fixed with Obamacare)).
And "functioning" was perhaps a poor choice of words. The US for example, after dramatically refoming its tax and welfare system in the 60-70es, have experienced ever growing inequality for which no end is in sight, without any resulting tangible improvements concerning economic growth. I didn't mean such a system when I said functioning. I mean it's a lot better than a lot of others, but it is not something I would want to rely on in the long term.