As somebody who works on computer vision, my general take on these things is that adversarial examples are like poison. It would be fairly easy to add poison to a water supply or the air intake of a large building and kill a large number of people. This rarely happens though. It's ok that water sources, buildings, and people aren't completely immune to poison. The safety requirement isn't that poison can't hurt. Inst…
1 and 2 are almost always going to be impossible in the US due to the first amendment (this is a feature not a bug) 3 doesn't seem crazy, but it would practically end up with caps, which might not be what you're looking for 4 This both: seems possible, and will basically never happen due to cost in every little jurisdiction
See Metromedia, Inc. v. San Diego for example.
#2 is expensive and difficult, but that's what we do for explosives, poisons, drugs, etc.