The only difference between theft and robbery is that robbery is a taking of property that is accomplished with a threat of violence or violence.
Bingo.
It still does NOT make your earlier statement correct, but I guess I understand the point that you are making... even though I think that you are oversimplifying the role of government and attempting to characterize it as something that it is NOT... which your oversimplification causes you (and several of your other anti-government proponents) to attempt to throw the baby out with the bath water.