I don't think it would be "much more effective" than trying to trick self-driving cars. Humans are (still, much) better at reasoning their way through ambiguou

I don't think it would be "much more effective" than trying to trick self-driving cars. Humans are (still, much) better at reasoning their way through ambiguous sensory input based on their abstract understanding of the world than AIs are. While an AI might specifically already know that a given intersection is supposed to be controlled, there are large numbers of driving situations in which memory (or maps) aren't very useful in dealing with. When it comes to self-driving cars, probably the way around attacks on signs or other static road features is just to fail safe even in situations in which you're mis-directed by road features (that is, you drive cautiously enough that even if you don't understand the road situation, you can find a way to stop without hurting anyone). But that's not a general AI solution, and may not even be a general self-driving car solution.