An individual in an anarchist society can NOT agree to be governed, because by definition, he is no longer in an anarchist society. Anarchy is the absence of government. When you agree to be governed, there is a presence of government, not an absence. That's like saying a pro-mother can still be pro-life while aborting her baby.
Free market capitalism isn't right for America because it works better. It's right because it's free (and it works better).