Earlier quoted context omitted.
It's not so simple - you can't simply follow the highway as you have done hundreds of thousands of times, because if the paint stripes have changed since Monday, then these might also be new (or temporary) stripes painted by a road construction crew overnight and you now must follow the new stripes.
Now imagine all people have Tesla, and someone makes a prank on the middle of a bridge, they paint a line that makes all traffic plunge down, imagine now that they are so confident they removed the driver seat, you have all those passengers looking on the windows on how their cars are driving them to their deaths and there is nothing they can do. So should this cars follow some line blindly? I think that this tech sh…
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.