Human drivers communicate with each other through subtle cues, body language, etc. Moreover, pedestrians, children playing in the street, pets running onto the road chasing a ball, construction sites, parades, protests, are all things involving intelligence and theory of mind that you can't reduce to "the goal is to point A to point B."
We can try to reduce these things. Most things can be reduced to "obstacles". If obstacles are behaving the way we predict, then they are logical, otherwise they are flagged as illogical. When i engage in "subtle cues" or "body language" while on traffic i never trust it. If someone starts to drive illogically i never try to predict what they will do next, i just flag them as illogical and prepare for the worst.
There is a way to solve all these issues: keep humans (and other animals) away. This is how it's done with railroads. Unfortunately, there's not a whole of advantage in eliminating the engineer of a train since the ratio of engineers to passengers is so small to begin with.
I think instead of flirting with this absurd fantasy of self-driving cars we should be doing more to invest in railroads and other forms of mass transit so that people don't need to drive at all. Europe and Asia are far ahead of North America in this regard.
Mass transit doesn't get you exactly where you need to go. In areas with lower population density, it's especially unprofitable and difficult to implement -- and even if communities can afford it, it will deliver people even FARTHER from where they need to go.
I'm a transit advocate, but there are some fundamental issues that need to be resolved first, especially in North America.
Even in Europe, there are a lot of places you can't get to or get to easily without a car. I've done long distance walks in England, for example, and once you get beyond cities and larger towns, it's often the case that there may be a once or twice a day bus.
