"The person in the driver seat is only there for legal reasons" - how do Tesla reconcile this with the "summon" feature? How can they market the summon feature and say the Tesla could find you on the other side of the country unless it has someone in the driving seat touching the steering wheel?
It's a demonstration of the technology they have, not of the technology that will be available to consumers tomorrow (the hardware is in the cars, the software isn't).
Part of getting the software deployed will be figuring out the legal situation.