"Once the platforms to rent out things, services or time are stable, textbook economics states that the cost of using them should fall." I'm not sure what text

"Once the platforms to rent out things, services or time are stable, textbook economics states that the cost of using them should fall." I'm not sure what textbooks say about economics these days, but the pure supply and demand economics assuming rational actors taught in economics 101 has never been a good model of real world behavior. Marketplaces are valuable because they provide monopoly profits. They are real estate, and participating in them requires rent.