Waymo's system doesn't depend on GPS for navigation either. They use their "realtime sensor suite" (lidar) to localize the vehicle position within the map. As

Waymo's system doesn't depend on GPS for navigation either. They use their "realtime sensor suite" (lidar) to localize the vehicle position within the map. As part of that localization, there will be a metric of how good the local solution is vs. the map. If a divider moves, for example, the data will be inconsistent with the map, and the software will know that something is amiss, without having to intelligently classify anything. The software can drive confidently when in a consistent environment, and drive conservatively when in an inconsistent environment. Generally, any object that isn't in the map will stand out obviously. That's where having stuff like cameras becomes useful. Asking a computer, "is there a construction worker in this 20MP image of a street?" is hard, but asking a computer, "is this 0.1MP human sized blob a construction worker?" is a lot easier. Waymo has been responding intelligently to bicyclist hand signals for years. "Is this sign shaped blob a construction sign?" is even easier. The lidar and mapping is a key difference between Waymo and Tesla. Waymo works because they have the big data infrastructure, and the budget to deck out every car with orders of magnitude more sensors and compute.