[pieceofthepuzzle]

Seems to me that so many things will have to be working properly, without a hitch, or there could be disaster.

First, would they be driving on roads upon which there would be no cars with human drivers? If not, how do you program the car to deal with unexpected things that a human-driven non-computerized vehicle might do?

What happens if the GPS or the road sensors don't work, or have a glitch?

What if someone decides this is a great terrorist target? Just disrupt the GPS or road sensor signals and watch the results..

[Smokin' Joe]

Deer, dogs, cattle, moose (yes, even moose). Too many unpredictable events occur even without other drivers, and that assumes that all else works as it is supposed to. That makes no allowances for snow, ice, blizzard conditions (well known around here), subzero temperatures, or a host of other natural and unpredictable events.

Even programming in construction detours would be a challenge.

While a lot of drivers out there are pretty scary behind the wheel, they retain the potential to react appropriately in sudden situations despite ordinary inattentiveness or poor skills.

A computer might not be able to do so, especially if it is installing one of bazillions of updates and security patches, etc.

Of course, compromise such a system with evil intent, and the potential for carnage is phenomenal, not to mention the potential for the 'removal' of individuals, while blaming a 'computer glitch'.

It'd make a great sci-fi plot, but I can't honestly say I see where it would be an improvement.