Anarchism /is/ about a lack of government, but more importantly it is about a lack of being controlled by institutions, economic forces, and people who should have no say in your life (hence why anarchist are also against capitalism, the church, etc). Therefore any form of governmental control is out of the equation. This includes institutions 'where people are in control of other people' (as another user defined democracy.)
And if we could opt out of being governed, it is was truly a voluntary system, it wouldn't be a government, it would be an advising body, with no ability to enforce its ideas without undermining its essential voluntary-ness. Such a system would be a waste of resources for all involved.