Human drivers aren't perfect, but their failure rate is known and predictable. The right software update, though, could have a bug that turns the whole fleet of

Human drivers aren't perfect, but their failure rate is known and predictable. The right software update, though, could have a bug that turns the whole fleet of autonomous cars into murder tanks overnight, invalidating all prior collected safety statistics and expectations. There's nothing that could make the whole population of human drivers unsafe all at once, we know the upper bound of the destruction we can cause. We've spent a century earning that predictability. With software, we'll never have it.