Sure, a bug fix for a routine being called is maybe easier to fix, but the real world performance is still the important metric to track.
I am not saying we shouldn't be critical of Tesla or hold them accountable for their product. My point is simply that their product doesn't have to be infallible for it to still be an improvement over the current solution.
A self-driving Tesla is not objectively better than a regular, human-driven car. The jury's still out on whether any self-driving car is even as good as the average human driver, so if one of them has a bug that causes serious accidents in reproducible situations, that's not better than the baseline situation it's being compared to.
Unless it goes of when it's not needed and kills you.
The same cannot yet be said about "self-driving" cars.
That assumes the pacemaker works more often than it doesn't. (Which is the case now.) It's an unstated assumption that doesn't always apply when generalizing your example.
Even if pacemaker fails 90% of the time 90% chance of death is better than a 100% without it.
Unless the person wearing pacemaker is driving a non-self-driving car.