> I don't see how GPS is a "nice to have". How does an entity know to get from A to B without some sort of navigation assistance? GPS ≠ navigation assistance.

> I don't see how GPS is a "nice to have". How does an entity know to get from A to B without some sort of navigation assistance? GPS ≠ navigation assistance. You can infer where you are on a conceptual map from reading your surroundings, especially signage. Getting a latitude/longitude estimate from the GPS network and trying to match it with an overly precise and possibly out of date map isn't the only way to infer your current position. It's only useful when you don't already know where you are, and computers are good at precisely remembering the path they took from the last known observed reference. Plus, self-driving cars need to be aware of their surroundings, and not solely rely on blindly following a hyper-precise map as a prescription of the road details ahead. Having the local observations become the canonical precision knowledge, and keeping the map as conceptual knowledge of how roads connect places, implicitly gains a lot of this sort of benefit.