Here are two quotes from the letter Tesla attached to their disengagement report:
"“For Reporting Year 2019, Tesla briefly tested an autonomous vehicle in autonomous mode on public roads in California. In April, we operated one vehicle in autonomous mode to record one demo run on a 12.2-mile route around Tesla’s Palo Alto headquarters. The route covered surface streets and highways. We did not experience any autonomous mode disengagements during this run and, as a result, do not have any disengagements to report for Reporting Year 2019.”
"“For background on how Tesla develops software capability, first, using industry best practices, we perform hardware and software in-the-loop testing, system-level and regression testing, simulations, test track and/or on-road testing (not autonomous), and a battery of cross-functional reviews, hazard analysis, risks assessments, and failure modes and effects analysis. Second, we rely heavily on fleet learning. Tesla is the only participant in the AVT program with a fleet of customer-owned vehicles in the hundreds of thousands. Virtually all customers consent to Tesla running developmental feature software, including for AV capability, in “shadow mode” during their normal driving operation. Features in “shadow mode” run silently in the background without actuating any vehicle controls whatsoever, which enables Tesla to test how features will perform in real-world driving conditions before we deploy them to the customer fleet. As a result, we are able to collect billions of miles of anonymized driving data remotely over the air, including on targeted roadways and in driving situations that we later use to train AV features to perform safely, consistently, and predictably.”
Just sharing for informational purposes.
https://electrek.co/2020/02/27/tesla-reports-fully-autonomous-miles-first-time-years/