The problem with most of these types of "attacks" is that they're about the same as any other messing with roadsigns or what not. There's no end of things you could do around the roads to cause crashes, but they're all illegal and ultimately low impact.

This is a lot more interesting though from how it highlights the difference between current machine interpretation and human interpretation of road signs: which is to say, explainable AI is still incredibly important - the ability to slightly discolor the signs and have a blackbox AI read something entirely different means the systems and trainers we have are not cueing off a "safe" set of inputs to deliver their interpretations.

From that context, this is very interesting and important work - and I would argue also points the way to at least some basic road safety standards for self-driving systems (they should be resistant to this sort of non-human perceptible visual distortion).