Human drivers don't run an RTOS and a deterministic bus system either. In fact, I would argue that very rarely do human drivers fail because of jitter or nondeterminism.
Suppose you make an autopilot in JS running on Electron on WinXP, running on VM on top of Puppy Linux Live CD. And you still manage to prove that your system is 100x more reliable than human driver. Should it be dismissed just because we don't agree with technology stack? The latency of this monstrosity would still be lower than human driver and maybe they would stay lower throughout the operation.
As an example, I worked on an embedded system that controlled electrical motors that was hard real time. The fast task time interval was once per millisecond. No matter what, that got called by the RTOS exactly 1000 times per second. When it didn't finish it's job in time, the result could easily wreck real world items or cause harm to people. Nobody even considered using interpreted languages in that project. The fast tasks all had provably run in much less than a millisecond. That means no loops that could be unbounded, no memory allocations, no recursion, no writing to flash, anything that was even slightly unpredictable was out.
So, even if you could prove that your system caused less accidents than a human driver when it was running well, it would be impossible to do an analysis that defined under what circumstances the system would be running well. Given that, it would not be allowed in a well-engineered real time or safety critical system.
That's the rub: how do you prove that? If your software stack is 30 million lines of code that was written by god knows who, I would argue it's nigh impossible without releasing it and seeing what happens, which seems morally irresponsible and legally negligent. If you follow strict rules in coding conventions and algorithms, it's easier to statically verify code is probably correct.