I can't even begin to imagine how that would be done in this case. While the downside of Bad Things in a Tesla car is not nearly as spectacular as in a late-1950s experimental aircraft, it seems all owners are in effect test pilots.

What I'd like to see is an emphasis on stupefyingly comprehensive test vectors.

Optional but actually semi-mandatory. You have to manually accept the software update to install it, but there was recently a case reported of someone who was refusing to do this and stay on an old firmware. Over time, Tesla gradually deactivated things like navigation and entertainment systems (if I recall correctly), claiming that they had upgraded their APIs and they were no longer compatible with the owner's firmware. In reality I suspect they are just punishing the owner to coerce them into upgrading their firmware.