I definitely agree with you that safety and security are huge issues for self-driving cars. I just don’t think the Trolley Problem, or its various permutations, is particularly relevant.
Estimates are that 1.3 million people die in automotive accidents worldwide, and I’m confident that virtually none of them died in trolley-problem-type situations. We can do a lot of good by declaring victory on the Trolley Problem and instead focusing on how to make self-driving cars safe in normal, common situations, and even (especially?) plausible corner cases.
The Trolley Problem — having to make an ethical decision about which of two horrible options to choose — is so rare as to make it unhelpful.
Declare victory and move on.