"Natural" monopoly!
So if a market is to be truly free, who is there to stop such abuse of power when it occurs?
I still prefer smaller government and lower taxes (a so-called "Night Watchman" State) to say... E.U.-style Socialism, but do not think that society's problems can be solved in one sector (at present), nor think that it would be possible to never raise taxes in cases of emergency.
The best we can do for now is have a greater balance of power before we can even expect to meet all libertarian ideals, that is, to limit if not outright abolish the "initiation of force".