Well, they weren't, not in California. E.g.: https://www.kqed.org/news/11231526/uber-to-state-weve-pulled...

In 2016 they tried just turning their autonomous vehicles loose in SF without regulatory approval. They got shut down. Rather than apply for permits, they headed off to Arizona, where the then-new governor welcomed them with open arms, an "anything-goes approach", and a lot of anti-regulation blather: https://www.nytimes.com/2017/11/11/technology/arizona-tech-i...