Granted, such vehicles must have drivers, and drivers must be able to control their vehicles – these are international requirements that date back to 1926, when horses and cattle were far more likely to be “driverless” than cars. Regardless, these rules, and many others that assume a human presence, do not necessarily prohibit vehicles from steering, braking and accelerating by themselves. Indeed, three US states – Nevada, Florida and most recently California – have passed laws to make that conclusion explicit, at least to a point.
Under Nevada law, the person who tells a self-driving vehicle to drive becomes its driver. Unlike the driver of an ordinary vehicle, that person may send text messages. However, they may not "drive" drunk – even if sitting in a bar while the car is self-parking.