I'm not super familiar with this space, or laws where Waymo is active, what do you mean Google/Waymo don't buy insurance for their vehicles?

Is having insurance not legally required? Do they just pay out when there's an accident where they injure someone?

In many states, including CA, individuals can post a bond instead of carrying insurance. Companies with fleets of vehicles can also self-insure. In both cases the car owner is liable to pay any damages that insurance would normally pay.

Large companies with fleets of vehicles often self-insure.

Interesting!

When I was much younger, I worked for a couple companies that had (what I would consider) large fleets of vehicles, and they all were insured through an insurance company. I guess I just assumed that's how it was. I wasn't aware self-insuring was a possibility. Thanks.

Companies can self insure. That doesn't mean they have to. Your accountant can run the numbers to figure out if it is worth it.

Often self insure means they still pay an insurance company to handle the paperwork, but when there is a claim the company pays it.

While I'm not sure of the specifics for car insurance.

For health care, a lot of large companies technically have say Anthem or whatever but the company pays out all of the claims and it's just administered by Anthem. So you may have seen a similar thing where all claims were handled by say Geico but it's not Geico's pot of money paying out claims.

Self-driving is probably still new enough that insurance companies wouldn't have good actuarial data to properly price the risks, so they'd just have to charge exorbitant rates.

It has been classic lore that Bill Gates couldn't get anyone to insure him after his younger years (see classic mugshot photo used as the silhouette) so he had to self insure. Not sure if completely true but I remember the stories.