I have been in the real world and understand what you are saying. Most of what you are describing however is hardware failure of some sort. The X,Y, or Z axis does not just go somewhere it is not supposed to. If you were to troubleshoot you would more than likely find that the computer followed it exactly as it was reported to it. Now the dirt on a sensor can cause a false report and from yours and my viewpoint the computer went somewhere it shouldn't. I probably don't explain it well but the computer did what it was told, that is all it can do. It is just like the old phrase garbage in garbage out. Somewhere along the line it got fed garbage, your speck of dirt for instance.
You say that if something goes wrong with a human driving that there is a good chance they can compensate. Maybe yes maybe no. There are accidents every day that prove this. Will computer operated vehicles be any worse or better? Only time will tell.
Don't get my wrong. I am not saying that computers should be driving our cars. I have a lot of apprehensions about the technology, but reality is that they are here. They are currently licensed for testing and on the roads in California as well as a couple of other states. Yes they have an operator that can hit that red button you alluded to earlier. I can't see us giving up that ability, nor do I think we should.
As I listen to some of the talk on this subject it is very similar to what occurred when we went from horse and buggy to automobile.