We'll have arrived at the automated transit network when they stop putting up road signs. The cars know where they are, and how to get there. Signs are for fallible ignorant humans.

GPS not nearly that reliable. There's a reason drones are moving towards computer vision rather than purely relying on GPS. The physical signs won't glitch out and show 100m offset because a tall building was reflecting GPS signals.

Maybe in a 100% automated system we would replace the icons with QR codes or something but physical markers will likely be here to stay.

> The cars know where they are

not if they're in a tunnel or a highrise canyon, or there is weather-related interference, or the maps have not been updated to reflect reality, or there is a detour for construction, etc.