As opposed to what?... Floor it? Just stopping is the safe default* that should be practiced by more human drivers, too.
*) In the general case especially within cities. There are exceptions - for example on roads with high speed limit like euro highways, where stopping for non-emergency reasons is banned anyway.
As opposed to not existing.
As opposed to any number of ways to provide for emergency override.
If I drive a car in the wrong manner, I am responsible.
If I just leave a car dumped somewhere on the street, unattended just like a Waymo, I am responsible.
Yet somehow Waymo and all the others are allowed to basically dump a special kind of litter all over the streets. There is no reason this has to be tolerated like there is no alternative. It's not inevitable or required or anything. It's absurd that it is allowed to happen at all in the first place.
It's absurd to ask "As opposed to what? Floor it?"