If I were made god emperor of some country I'd switch everyone to autonomous cars as soon as they were safer than normal driving. But sadly I'm not and both Tesla and the government are going to be constrained by public opinion. And one important aspect of that is that people are more accepting of danger when they feel like they're in control than when they don't.

So for a successful rollout they need to be much safer than human drivers. This is something that looks achievable. But if you try to push them out too early you might get a backlash that delays progress and costs more lives in the long run through slower adoption when they're ready.