“Why do we care about safety?” says Peter Norton, a transportation historian at the University of Virginia. “Because we care about human health.” Norton warns that the autonomous future will result in less walking, more sprawl, and—without dedication to electric propulsion—a huge spike in pollution. “When your car drives itself and you can spend the commute doing whatever you want, who cares if a trip that used to take 20 minutes now takes an hour?” he says.