Interesting partial list of examples, which I agree with. What is becoming more clear to me is that the diversity of often nonstandard roadsigns out there, sometimes with conditional driving directions, means that recognizing a sign against a pattern may not be actually get us there. There may need to be text recognition and comprehension functions added to the AI in order to deal with these and other nefarious cases, given that sign creators seem to delight in inventing ever more edge cases for sign recognition.
Such examples also illustrate, I think, that relying on a remote database is unlikely to ever be a satisfactory solution. I can't think of any other technology but vision systems that will ever compete with the proliferation of states sign types, conditions, and especially with dynamic sign types (construction on this mile today, on the next mile next week, ...)
Duplicating the efficacy of human recognition and understanding (when the human is focused and not distracted, sleepy, or intoxicated) is no small task.