This is not the issue with that statement at all, and for the record I'm skeptical of cars sharing data to augment what they see (because this leaves them open

This is not the issue with that statement at all, and for the record I'm skeptical of cars sharing data to augment what they see (because this leaves them open to attacks that are unique to self-driving cars). The problem with the statement is that it, as the GP post says, ignores the fact that a human driving a car is no less likely to barrel through an intersection with a missing stop sign. There are a few other low level problems with this scenario as well, mostly hinging on the weird idea that self-driving cars are just going to barrel into an intersection without a stop sign as if there are no other cars going through it. This is why they have radar/lidar/whatever else.