Computers are still too stupid.
One of the analogies I've seen at a speech on the subject went something like, "A computer can detect an object in the roadway, but it can't yet tell if it's a paper bag that can be safely run over or a rock that's apt to damage the car."
This was a few years ago, so I don't know if it's still true or not, but it does demonstrate the programming challenge in processing something exceedingly simple that even the most inexperienced human driver would be able.
But the computer will do the sensible thing and reduce speed, try to avoid the obstacle, be it a paper bag or a rock. One novel modality of violent-neighborhoods robberies has been "fill oranges or other fruit with nails and let them on the road; unaware drivers don't make any effort to avoid fruits on the road, get stuck with one or more flat tires, profit".
Another thing to think about is: the computer was not on in three of the four cases; yes, computers can be pretty stupid when they are not working.