[LorenPechtel]

Why in the world wouldn't they?

It's always how vehicle safety data is calculated.

With human drivers it matters--high mileage drivers are more likely to be driving tired or in poor conditions, low mileage drivers often are losing their abilities. Thus you see elevated risk on the ends of the curve. That doesn't apply to machines, though.

[dominotw]

wouldnt we mass approve these everywhere if that was true then?

[OkayPhysicist]

They basically are. Waymo's basically spreading as fast as they can 1) verify they can drive safely in the local conditions (SF has fog, but no snow or ice), 2) work with local governments to set up a "what happens when a cop pulls over a Waymo" procedure.

[xnx]

Uber and misguided anti-car advocacy groups are lobbying against them. Uber doesn't want the competition. Anti-car advocacy groups are deranged in their ire toward anything that looks like a car and have totally lost the plot on transporting people safely, promptly, and affordably.