Markets are not free. They are the product of immense expenditures of land, labor, capital, and enterprise; for they cannot be maintained at any considerable scale except under conditions of good political order: laws, lawfulness, an efficient and just system for the administration of justice, the enforcement of agreements and the adjudication of disputes; safety and security (furnished by honest police and lethal warriors to deter piracy, crime, and plunder); reliable weights, measures, and media of exchange; complex financial arrangements (banking, brokering, insurance, and so forth); sophisticated transportation facilities (ports, highways, bridges, etc.); a prosperous pool of prospective customers; and the infrastructure to support all these functions (sewers, waste facilities, food, housing, and so on).
Markets do tend to form wherever people are gathered together, it is true, and no one needs to arrange for this to happen any more than languages need to be administered. But like languages, markets cannot flourish except at scale: below a certain number of participants, they wink out. And the achievement of that scale requires political order over a geographic region and a population large enough to form a profitable target market for sellers (whether foreign or domestic).
Political order is of course good for other things than markets. It is the forecondition of any civil prosperity, along any dimension: as, not just wealth, but health, sanity, sagacity, happiness, righteousness, holiness, fecundity, creativity. All these in turn feed back into the vigor and sanity of the political order, and its fitness to conditions. So they do likewise with markets, and vice versa.
Markets, in short, are expensive. Much is paid to facilitate them. Because they are not free in fact, they ought not to be available for free. They ought to be available only in exchange for payment. How ought those payments to be priced, and how collected?