Bernie Sanders attracted attention this week by declaring AI a “public resource” and calling for a 50 percent tax on AI companies to fund a sovereign wealth fund. Critics reacted by saying the idea proved that Sanders doesn’t understand AI or business, which is probably true of both his supporters and many other Americans. The same critique can be made of those charging monopoly control by agribusinesses like supermarkets and meat packers, industries with minimal or even negative profits.    These barely treading water agribusinesses are cited by economist Noah Smith in explaining his reversal of understanding on market power. He had read the economics literature on the adverse impacts of monopoly power, which le...