Well, if you really want to drill down on this example: the barber doesn&#x27;t have substantial interests in which type of haircut you get. Tesla has substantial interest in which kind of carbon tax you get -- high carbon tax would be a boon. Doesn&#x27;t materially effect how good an idea carbon taxes are, though.<p>Also, do people ask their barber what haircut they should get? I have only ever done a buzz cut or given a description &#x2F; picture.