California Senator Scott Wiener is introducing a new set of bills to make streets safer across the state, including one that would change how you drive.
Just fucking electronically limit the max speed to the maximum allowed in the country. That would solve most of the issues and work 100% of the time. Also, I don't care that in your fantasy scenario you have to race to a hospital at 100mph because someone cut of his head with chainsaw and there's no ambulance service.
If you want to race on a airstrip or a racetrack buy a race car and take it there on a flatbed. Driving racecars on normal streets doesn't make sense.
You will still have issues with people going 30mph in 20pmh zone but it's a good compromise: you're reducing the most deadly high speed crashes but the solution is extremely simple (it doesn't require GPS or image analysis) which means it will not have false positives, it will not affect the price of new cars and it will be better for privacy. It can also be retroactively applied to many existing cars so you could introduce it sooner.