I obviously don’t know for sure, but at least it’s conceivable that, in fact, it may be the case that erratic behavior of other drivers, caused by someone else driving slower than them, leads to a significant number of accidents every year that would not have happened had they been driving at the same speed as everyone else.
In this case, forcing the self-driving vehicle to never go over the speed limit literally means you’re knowingly choosing an option that leads to more people dying instead of less.
I think there’s a pretty clear moral dilemma here. I’m not claiming to know the right way forward, but I just want to point out that strictly following the rules without an exception is not always what leads to the best results. Of course, allowing self-driving cars to break the rules comes with its own issues, but this just further points to the complexity of this issue.