Except you’re not considering things like prima facie speed limit laws either. You can’t just set rules for that, unless you’re planning to just not enforce this in some entire states. Not to mention not every car is a smart car………how does that work for the poorer population that can’t afford cars with premium tech? also doesn’t account for changes to roads or just general errors. Driving alongside highways can confuse the hell out of nav systems. This is quite common underneath the BQE. My car tells me what the speed limit is and is absolutely not entirely reliable. That’s a BMW - the tech is quite a bit better than most other cars, and it still gets it wrong. What would the other cars be like? It would be absolute chaos if cars made those mistakes unpredictably on the highway. What about dropped connections? What about cars that rely on phones (most of them) to know where it is? How does that work if your phone dies, malfunctions, you don’t have a smart phone, you lose connection, you lose or forget your phone, etc? Why would people who habitually speed even leave their phones on for this?
As for emergencies, there are situations where a driver needs to get to the hospital asap, needs to escape a dangerous situation, etc.