Good autonomous vehicles don’t work primarily by sensing and detecting the roadway, they work by sensing the environment and having a complete, detailed 3D map of drivable areas, matching their environment to the map as they go along. This only requires annotation of the terrain, not clear road markings or anything like that.
The 3D detail of the environment is the smart roadway. With always-on GPS and an incredibly detailed map of the environment stored on a honking hard drive in the trunk, there’s never a question where you are in the world.
In fact, now that I think about it, this makes reduced infrastructure possible, since you don’t even need things like signs or streetlights in an all-autonomous world, and can even get by with narrower lanes.