IN A limited sense, cars have been “driverless” for a long time — ever used cruise control? — but they are about to become far more capable, and soon, revolutionizing the way people get around. Transportation Secretary Anthony Foxx promised last week that the federal government will smooth the rollout of driverless vehicle technologies, removing unnecessary regulatory roadblocks and delays. But realizing the benefits of driverless technology will require more than smart regulation; companies and the government will have to convince the public that driverless cars are safe.