OK well let's argue about the semantics of "autonomous" instead. To me, it means the vehicle's on-board systems should generalize to safe and non-disruptive behaviors under all circumstances. In this instance they should have been able to either navigate to a depot or at least pull off the road.

I think that’s a perfectly reasonable standard for a normal operating environment.

In emergencies I think “safe” is preferable to “non-disruptive.”