Todd Zywicki is normally one of the worse authors I've criticized at the Volokhs, but if it's true that he helped the ongoing Department of Justice efforts to break monopoly power by full-service real estate agent syndicates, then he's done something significant to help the environment.
The full-service real estate agents, many of them organized into Realtors Associations, use their monopoly power to bump up commission money (by prohibiting discount brokers from making use of listings of for-sale properties), and then funnel some of that money into anti-environment, land use politics meant to increase sprawl, development, and real estate deals. I've encountered that problem in the course of my own professional work.
Of course many full service agents are just fine people, but their organizations are terrible for the environment, and are fleecing customers at the same time. A competitive market would have a lot less slush money floating around for political shenanigans.