Daniel in SD makes many good points, and although Tesla as a company cannot say this, I can, so:
The reality is that Tesla has now created an entirely new driving risk. Prior to the introduction of Tesla's self driving systems, no other system available to the public had the ability to self drive "enough" so that there was the possibility of what I would call "induced negligence."
I use the word negligence because its legal and, I think, helpful. Drivers are already negligent to an unacceptable degree, but up until now there have only been rare instances about a feature of a car which actually caused behavior which rises to the level of negligence. There is one exception I will save until the end.
Regardless of what caused this accident, there must be some accidents caused by such induced negligence. But that is not the end of the analysis by a long way.
The thing is, there is no way of knowing if accidents caused by "induced negligence" where a driver is lulled into a state of inattentiveness by a Tesla EXCEED accidents prevented by the same Tesla system, which not only controls the car but sends out warnings to the driver constantly. Overall data suggests that incidents of induced negligence are rare (although they are highly publicized), and incidents of Tesla cars preventing accidents must, logically, exist, but at the moment are difficult to quantify (with the exception of a couple of times Teslas pulled over and saved drivers who fell asleep).
Just because the risk is new, does not mean its "unsafe" -- that's because safety can only be calculated overall. Because if there are 3 accidents caused by induced negligence but 10 accidents prevented by the same system its safe - that's the definition of safe. It was unsafe for those involved in the three accidents, but that's not the logical definition, nor is is the correct definition from a public policy standpoint, which is what counts.
I mentioned the exception though: sports cars. I can't really think of any reason that in a country where the speed limit is, at most 75 mph, that cars should be able to reach 90 mph or more, let alone the 100+ mph that many sports cars can do. This is an example of a "feature" of the car which directly causes more accidents, and more serious accidents, then low performance cars. Yet you never, ever hear of any movement to ban sports cars, or engine capability.
Come to think of it, there is another example, and that is the converting of two seat pickup trucks into SUVs. Which induced drivers to drive a "car" with terrible handling characteristics and a much higher risk of rollovers as if said SUV was a lower slung sedan. That did get some publicity, but despite the obvious logical connection nothing happened.