Probably regulators, because insurance companies are better at statistics.
The one thing I could see insurances worry about is correlated risk. Imagine if an accidental push installs a bad development version of the autopilot on all cars instead of the 2 test vehicles with extra sensors, causing a much higher crash rate. Add a broken auto-update mechanism preventing a rollback, and it could take a day to mitigate and a week to fully stop the crashes, and during that time a lot of cars could crash. As long as it's no worse than the crashes resulting from e.g. a day with severe weather, it'll probably be fine, but if it significantly exceeds that, insuring self-driving cars could become too unpredictable, and thus too risky for insurance companies.
The Tesla press releases? It's the kind of uncritical analysis that you would expect from a company trying to market something.
Food for thought: By considering only automated and mnual driving you exclude basically all possibilities. Hybrid systems that are designed around the limitations of humans and machines seem to be a much more promising but less flashy solution if safety is the goal. This approach has a long history if you consider things like ABS and the traffic fatality statistics suggest it actually works. (Crash mitigation technologies surely muddy the waters.)
> By considering only automated and mnual driving you exclude basically all possibilities.
I'm not comparing Autopilot to some hypothetical future system. I'm trying to determine whether the risk from Autopilot is comparable to human drivers as they drive now, because insurance companies have clearly shown that this is something they're willing to put up with.
A computer making mistakes isn’t acceptable, every instance will be seen as a liability and a huge one.
computers will not be given the benefit of the doubt that humans have
[citation needed]
Insurance companies will just look at the stats. And you better believe they'll jack up your rates if your self driving car crashes. You'll be held responsible, like it or not.