That is true, and indeed what happens with some passive index funds, for example. However, from my experience, when looking for profits, people tend to prefer

That is true, and indeed what happens with some passive index funds, for example. However, from my experience, when looking for profits, people tend to prefer to arb inefficient markets before they choose to work on larger scales. So if one can choose between charging more than one provides, or charging "fairly" but at giant scales, the first step of the evolution will be the arbitrage.