TTT //what do they do when there is no driver? //
They blame the software, so they correct it, send the bugfix automatically to all cars using it and move on. Unlike human drivers, who don't seem to be able to learn; they still use cellphones, drive whilst drunk etc.
You say you have worked in IT all your working life TTT. Would you care to expand on that? My wife worked with IT for many years, filling in numbers on a spreadsheet. I worked in IT for almost 50 years, programming everything from calculators to massively parallel machines. Having you ever been involved with R&D? If so you will know that even after many years problems crop up with programs as new fields are explored and hitherto impossible situations become possible.