The article is saying that it may be difficult or impossible to prove that self driving cars are actually safe. The Tesla issues and recently released sensor shortcomings are damning and really put a dent in my faith of this technology.

An example from a recent road trip I was on: I was travelling down a suburban street with cars parked on the side of the road. There was a car parked with a relatively high undercarriage, so that from a distance I could see under the car through to the other side. I saw a pair of shoes toward the front side of the car, which I (correctly) deduced were connected to a human being. In anticipation of driving past a person who might step out in front of me I slowed down and made sure to pass safely.

Tesla, on the other hand will drive at 70mph into a concrete divider if some paint on the road is smudged.

We've got a ways to go yet I think.