You could say the same for trains though - they follow a track in a similar sense to Tesla's autopilot. Someone could perform a "prank" by putting something on the track in order to derail a train. How often do you see that happen? Painting a line on the road is obviously easier to do, and could also happen by accident, but I think the chances of any danger are extremely low.

Hopefully when we start removing the driver from cars with autopilot, they will be following some sort of under-road NFC-like guidance system rather than painted lines.