When automobiles were first created, they were curiosities. As they became more available, people used them to travel longer distances.
The automobiles were setup to have lamps, so the drivers could see better in poor light or fog.
As time went on, municipalities set laws. A poorly lit automobile might be a menace to carriages and those using horses.
Laws eventually setup rigorous design criteria for the lights at the front and lights at the back.
I predict that self-driving cars will not fully appear for a long time. Governments want a responsible party in the case of accidents. Someone culpable if a device fails.
The technology for self-driving will still advance (making it easier to drive).
Probably reducing the fender-bender accidents. Which was why the automobile lighting was considered important.
If safety driver systems prevent those accidents, a driver might become lulled.
So, I suggest using the backs of other people's cars as a display surface.
A viewable screen that the car behind can be seen.
The energy required for displays is reducing quickly. Less that incandescent car lights use.
That display could have simple driver awareness features for the driver directly behind.
Even selectable content. News stories. Chapters of the favorite books. Tied together with audio in the car behind.
A system which enriches the driving life and helps keep driver attention to the car ahead.
I actually might like to be a part of the first mobile book clubs.