In a well-functioning market, the price of goods should eventually shrink to their cost of production. If they do not, that's a monopoly.
2. In a market of commodities, prices are determined by multiple aspects of the surrounding social power relations.
3. In a market, there tends to be a concentration of capital leading to an oligopoly or monopoly; this is more likely than a shrinking of prices to the cost of production.
Honestly, I wish more journals mandated open for a fee—I want my work open, but the choice makes it easy for universities to decline to pay—if mandatory, they would gladly pay 3x to have their researchers publish in top outlets (I’m in administration for a large R1)