Somewhere out there is the HAL9000 of car computers, ready to keep drunk, distracted Dave from driving and killing himself or whoever he mows down, but we're not there yet.
So I am willing to settle for a baby step. I want all cars, starting with the 2019 models, to be equipped with a turning sensor. If the human driver fails to active the turn signal when at a stop, the car will pause, blow the horn and active the turn signal for 2 seconds before allowing the turn to be completed. Just at a stop, so that it doesn't cause a problem in an emergency turning situation where you are trying to swerve out of the way of some other vehicle doing something
It would take one day to Pavlov the human operators into using the damn turn signals at intersections.