Regulation is one of the major factor that slows down. You need more and more test cases to achieve higher reliability, but data collection at scale need approv

Regulation is one of the major factor that slows down. You need more and more test cases to achieve higher reliability, but data collection at scale need approvals and regulators want to see if it's reliable enough to approve. This chicken and egg problem is not something easy to solve since at its heart it's a trust problem. Tesla was an exception because they choose to put all the responsibility to the drivers by making it technically ADAS but marketing it as "full self-driving".