Waymo is already doing rides without a safety driver to passengers who have signed their NDA. Which means they're confident of their behaviour on some really difficult problems, like pedestrians.
Sure, it'll be at least a decade (if ever) before they can do everything a human driver can do, but a "meaningful product" they pretty much already have.
They don't have to support driving in blizzards or on unmapped roads to be a meaningful product. Uber is useful even though it's only available in large Metro areas, Waymo can be a meaningful product even if it doesn't work in many places.
Sure, it'll be at least a decade (if ever) before they can do everything a human driver can do, but a "meaningful product" they pretty much already have.
They don't have to support driving in blizzards or on unmapped roads to be a meaningful product. Uber is useful even though it's only available in large Metro areas, Waymo can be a meaningful product even if it doesn't work in many places.