This one gets trotted out regularly and usually there's someone who points out that most accidents are pilot error. But as rick.shaw points out in his post this is to ignore the reality that almost every day pilots step in when the automatics and the technology fail to cope. I'm sure every Airbus pilot has a 'What's it doing now?' story. Even the AF447 accident was initiated when the the autopilot disconnected in response to turbulence. So much for the automatics. Certainly the human input compounded the the problem. But I daresay when something similar happens again there will be a different result with the benefit of hindsight.
Actually single pilot would effectively mean no pilot. The old joke about the pilot and dog is close enough to the truth. But I think we're a long way from that. The technology is simply not mature enough, not reliable enough and not intelligent enough.