Not quite the same problem but the result is pretty much the same. The fact that computer vision can be fooled by attacks like these are lower risk than we might imagine. The more important question is what is the likelihood that such conditions occur naturally and randomly.
Edit: also, the summary comment about this being the first time a physical object was used to fool a commercial classification system sounds... dubious...
1) people care much, much less about "hurting" automated systems, and
2) people feel much less responsibility for accidents & failures if they are separated by a level of indirection of automation
3) people feel much less responsible for mass actions that affect anonymous people far away
Together, those three factors will indeed cause more incidents of people attempting to fool the self-driving cars. Especially if done by displaying malicious images via mass devices, like the light-up info boards, electronic billboards etc.. I don't expect much more actual accidents, tho.