Exactly, Waymo were talking about this a few year back, they found that building it up gradually will not work, because people would stop paying attention when

Exactly, Waymo were talking about this a few year back, they found that building it up gradually will not work, because people would stop paying attention when it's "almost" there, until it isn't and it crashes. So they set out on having their automation good enough to operate on its own without a human driver before starting to deploy it.