There have been self-driving busses that use such painted guides on fixed routes; here's a story where Las Vegas was testing such a system using the tech of 22

There have been self-driving busses that use such painted guides on fixed routes; here's a story where Las Vegas was testing such a system using the tech of 22 years ago: https://www.nytimes.com/2001/07/26/technology/what-s-next-it-s-a-trolley-it-s-a-rail-car-no-it-s-an-optically-guided-bus.html https://www.nytimes.com/2001/07/26/technology/what-s-next-it... But, I doubt they'd be much help for passenger cars on diverse urban per-trip routes: * roads are constantly wearing & being trenched or resurfaced; the lines would often be broken or need refreshing, necessitating an effective 'lineless' mode * cars often need to improvise (including briefly into oncoming lanes) to get around temporary blockages, and need to pull away from the major maintained lanes – again requiring confident off-line operation * after car sensors/decisionmaking can handle all the other challenges & collisions/traps to avoid, merely following lanes (when needed) is not hard at all: guidelines help with an easy, essentially-solved problem but not the actual potential deployment blockers Full-unattended self-driving cars are working pretty well in SF right now - on a nighttime walk you'll see many, which are behaviorally only a little more cautious/tentative than human drivers. So, it's only the branding & empty driver's seat that distinguishes them.