It's not like all pilots without that much glider experience are 'unsafe' because they can't recover in that extremely particular set of circumstances.
Even if we ignore the possibility of remote control, you don't need an autopilot that's better in every way than every existing pilot. You just need one that's better than the average pilot.
Let's use a different argument, just for the sake of it. Let's assume there exists a medical device, which never fails on its own, but due to operator errors 1/10000 patients who use this machine die.
Now someone makes a fully automated machine,but due to problems with programming it kills 1/100000 patients it treats(completely on random). Even though it's 10x better than your average operator, such machine would be banned from the market quicker than you can say "litigation". In our society human errors are much more easily forgiven than computer errors, because everyone believes that they could have been prevented. And therefore, a truck autopilot wouldn't need to be just better than your average driver - it would need to be absolutely perfect. And I don't think we are ready for perfect yet.
Well no - the problem with problems is that you can never predict all of them, and complete autopilot would either need to exhibit strong AI to deal with all(not possible right now) or have them all coded in(also not possible). Not to mention that complete power loss can, and has happened before - even if the steering still has power, without a computer running it won't do much good without someone who can move the stick. Or look at the landing on the Hudson River - would any computer ever decide to try it? I think the answer is no. If we had a ridiculously good AI, I think it would decide to crash land the plane somewhere with no people. River has people. There were bridges in the way. AI might not be 100% capable of gliding the plane with no engine trust and broken sensors -it would have simply not tried that landing. That plane only landed safely because the captain had experience with gliders and knew what to do.