Think of it like human intuition. We haven't developed left-brain logic AI yet, but we are getting closer to training AI to outpace a trained human. They can look at a picture and say "That's a dog". That's an intuitive thought, not a logical one. A car could say "this situation feels dangerous", and ask the drive to take over, or it could just react and steer intuitively. It might not be able to reflect on its actions yet, but that doesn't mean it couldn't learn to drive.

Not that I think we WILL get to full self driving any time soon, but the car not being able to explain itself doesn't prevent us from getting there.