Actually the article states that the driverless rides are limited to a subset of the total Waymo test area in Phoenix, which has nothing to do with legal restri

Actually the article states that the driverless rides are limited to a subset of the total Waymo test area in Phoenix, which has nothing to do with legal restrictions but with how confident Waymo is in their technology. And, yes, some (maybe a big) part of Waymo being in Phoenix is the regulatory environment, but I bet a lot is also that there is no snow and other challenging weather conditions.