Your joke is not as far fetched as one might think! There have been multiple instances [0][1] of a Tesla (and also other car makes, for that matter) where the image recognition system could be tricked.
I wonder at which point we'll deem fooling a autonomous car a misdemeanor instead of changing the underlying AI system.
Too be fair, so do a lot of human drivers. Something about motorbikes makes them difficult to perceive. Not sure if it is car pillar design, not expecting to see them there (a prior of just looking for cars) or just a small frontal area.
[1] "Tesla does not see you if you are pushing a shopping cart" https://www.youtube.com/watch?v=Zw51rMUJFfY