And you'd still be a lot more worried if an autonomous system threw it than if a human did. Autonomous systems making mistakes (especially the potentially deadly kind) triggers more anxiety. Almost any example you can think of sounds worse when an autonomous machine is involved because it's one more thing to worry about.

I think you missed the context slightly. OP is saying that there are cheap and unsophisticated way to fool the Tesla autopilot system, in addition to expensive ones. If an autonomous system threw the rock vs a human, that has nothing to do with OP's comment.