Some observers have commented that another name for the “Black Market” (or maybe a more accurate one) is the Free Market.
Your observation and that of "some observers" is valid, ... as long as the whole story is told.
The Economics of the Marketplace are well researched and recorded, and a Free Market Marketplace is extremely rare.
Almost all Marketplaces have outside forces acting on the Market that render the Marketplace no longer a "Free Market".
It is the knowledge of the existences of these forces and their effect on Supply, Demand, and Price that is the whole story, and what determines the quality of that Marketplace.
Be Aware, and Beware.