There's nothing to "get". Despite all wishful thinking, the income tax is currently the law of the land, and wages are subject to it. The tax evasion crowd would have you (incorrectly) believe that through tortured semantics, when the tax code refers to the "United States", it really means only Washington DC or other federal territories. This is why such cases usually have the evader claiming to be "a resident of the sovereign state of (fill in state name here)".
And HR 25 would make all this mental speculation a moot point.
http://fairtax.org