monopolies in a free-market system is an authority. One can claim that they should expire faster or exist with less frequencies, but an authority is an authority, and with it it can exert pressure on what would be a balance between supply and demand.
If we look far enough into the past, large enough monopolies are indistinguishable from governments. The Hanseatic League had their own armies, their own laws and even their own cities. Under their rule they fully controlled supply and demand, including price, which no longer makes it a free-market system. Still, they aren't what we define as a state (definitions...).
Taxation don't violate a free market. A free market need laws, which in turn require police and military, which in turn need to be paid (which distributes money). If everyone has to have their own police, military and laws, everyone becomes small islands of states. Those states then violate the supply-demand market, and thus you no longer have a free market.
There is no free lunch here. One can try to redefine what a free market is, what socialism is, what a state is, what a authority is, what taxation is, what interferences is, but it will just ends up arguing definitions.