The finding that agent-owned homes are on the market longer and sell for more suggests that agents do deploy their specialized knowledge to maximize their profits rather than those of the homeowners they represent.
Like physicians, automobile mechanics, and attorneys, realtors know more about their area of expertise than the people paying them for advice. In the absence of properly structured incentives, experts can use their specialized knowledge to further their own interests at the expense of those who hire them. Car mechanics can recommend more expensive repairs than are really necessary, attorneys can charge high fees for services that reasonably intelligent consumers could perform themselves, and realtors can give sales advice that maximizes their profit rather than that of the homeowner.