I think what’s missing is what the software allows. It could be BMW/Merc etc are way more conservative on what the allow the system to do and when they force the driver to take over. In certain contexts Merc is actually willing to assert and stand by a higher level of autonomy than any other manufacturer: (https://www.motortrend.com/news/mercedes-benz-drive-pilot-le...). Taking that at face value it’s possible they can do it and choose not to because they don’t want the liability. Whatever systems are in regular cars are then either borked or deliberately have less hardware.

Tesla is uniquely risk tolerant for better or worse. You also don’t hear about people getting into accidents in a BMW on self driving because they don’t make the same claims and have tons of safeguards.