Sure but the public sphere needs funding either way. We're not going back to the Roman empire where the fire brigade was a monopoly controlled by one senator (Crassus I believe) who becomes the richest man in Rome by providing "a service" that should be a part of civil society.

In the Greek world a fire brigade was called a "church", or the root of that word in Greek, and local groups pooled resources. States will need to be held together by something you can call voluntary taxes. They're not really going to be voluntary because there will be social consequences enforced by society on anyone who thinks a private fire brigade (who are really arsonists with fire trucks) is a good idea.