Your understanding of what the most advanced simulation and modeling technology exists is incorrect and holding you and the industry back. This will prohibit anyone from getting remotely close to L4. Most will go bankrupt and harm more people for no reason. The gaming based technology being used now has far too many architectural issues to create anything close to a digital twin. And folks are not modeling active sensors correctly. DoD/aerospace simulation technology, augmented by knowing how to make proper active sensor models, resolves ALL of this to a full L4/5.
(This approach would rely on real-world data to inform and validate it. However, over 99% of that shadow driving will not be necessary. And safety driving would be even less. And when that is needed there is zero need to involve the public as test subjects.)
Be glad to prove this to you.
The Autonomous Vehicle Industry can be Saved by doing the Opposite of what is being done now
Simulation can create a Complete Digital Twin of the Real World if DoD/Aerospace Technology is used