They are vans.

> They are vans

I was in a Jaguar. The one they show on their site [1].

[1] https://waymo.com/phx/

They were vans: https://support.google.com/waymo/answer/13559409?hl=en

Part of this announcement is the completion of retiring our Pacifica fleet. So while we used to have the vans on the road in Chandler, you'll now see the same vehicles that were in Downtown Phoenix and San Francisco.

I haven't taken one since they announced the change (weirdly, I'm in a part of Phoenix that's pretty walkable), but I think it will be 3 in the rear bench and one in the passenger seat. They've been pretty clear that they don't want people sitting in the driver's seat, and I'm guessing that will continue to be the case with this change.

Yep, three in the back and one up front, driver seat empty. (The door won't open for you anyway)

I wonder if there's some regulation behind why they haven't got rid of the traditional front-facing layout entirely and replaced it with train carriage style seats around a table?

That would be a very expensive modification to make on all their cars.

These cars still have to meet all federal crash safety standards. Modifying the seating position would also require modifying the airbags, seat belts, seat belt pre-tensioners, etc. Then the vehicle would have to be crash tested again to ensure it is safe for the passengers.