That’s clearly unacceptable. It needs to gracefully handle not having that fallback. That is an incredibly obvious possible failure.

Things go wrong -> get human help

Human not available -> just block the road???

How is there not a very basic “pull over and wait” final fallback.

I can get staying put if the car thinks it hit someone or ran over something. But in a situation like this where the problem is fully external it should fall back to “park myself” mode.