Going off what fishpen0 said, Waymo actually has sensors on it to detect things and can "understand" its surroundings much better than Tesla cars can wish just cameras.
I've ridden in Waymos and they are smooth riding. After the initial "OMG! There's no driver!" You kind of forget about it. You get to your (limited area) destination safely and without much hassle.
I can go more in depth if ya want.
Interesting, when I took Waymo, it was cheaper than Uber and Lyft, pre tip.