It is in principle possible to make software as close to bug-free as one wants; it is just a matter of time and resources, that is, money. OTOH, it is impossible to eliminate human error beyond some level quite far from perfect.

Funny. I would have made the exact opposite argument. It's possible to train and educate a human being to be very safe and to use good judgement, but impossible to find every possible bug in a piece of complex code, and impossible to code something so that it can deal with all possible contingencies.

I don't think any rational person argues for "all computer control" or "all human control". Everyone agrees that we still need people in the cockpits because electronic systems, while good and useful, can't do everything. I don't think anyone in their right mind is arguing for electronic systems that can't be overidden.