They supposedly use trip info for their own advertising. Says also "in some cases" shared with third parties for ads.
"We collect usage data that includes trip history, buttons or links you click on our mobile app, in-vehicle interfaces, wait times for our vehicles, and other actions you take with our products and services"
"We collect information about your location in a few different ways. When you take a trip, we collect the pickup and drop-off location and details about the vehicle’s route."
"We may also use your information to personalize services, advertisements, content, and features, communicate with you including marketing (which you can opt out of), service, and account messages, or communicate other information we think will be of interest to you "
"We will retain information we associate with your Waymo account, such as name, email and trip history, while your account remains active."
"Waymo will not disclose your personal information with a third party unless one of the following applies:
...
- We're involved in a merger, acquisition, reorganization or sale or transfer of some or all of our assets
- In some cases to help us tailor ads and offers to your interests as detailed in the U.S. state law requirements section
- Comply with any applicable law, regulation, legal process, or governmental request
...
"
https://support.google.com/waymo/answer/9184840#zippy=%2Cinf...