that people can still steer and accelerte and slow down with just sensors and you can use half of the fuel and aloowing better response aand reduce power from the engine and the sensors make the car safer to drive . but it may not be safe to drive computer driven cars because of malfinction and that can be dangerous and they have to wait to make sure that is is reliably safe to drive it may not be as easy as they make it seem. sometimes the driver has to take over to pull in and out out of driveways to be on the safe side but the driverless car runs on electrical cables wich may not be safe that runs through radio signals to the front of the car. This may be alot of work to just drive a car beacsue of smarter roads and they need a whole lot of sensors on the car but they are still waiting on the law.