Well, I think that one problem is that the automation is not giving up; there is not handoff occurring. It's reporting "all's well" until fractions of a second before the crash, if that. This means that it's up to the human to remain constantly vigilant and identify abnormal situations.
Of course, when you consider that an overhead road sign and a stopped semi trailer "look" the same to the systems involved, it's not surprising that they think that everything's OK.
Of course, when you consider that an overhead road sign and a stopped semi trailer "look" the same to the systems involved, it's not surprising that they think that everything's OK.