The list is much longer. You're driving past a kindergarten; watch out for children. You're driving past a school. You're approaching an area with many users logged into Google so watch out for pedestrians. You're crossing a bridge. You're passing a point with an unusually large number of accidents in the past.

If that isn't to become some sort of text-to-speech database dump about the area, there has to be a good theory of the conditions for what's worthwhile. And I sense that the natural conditions are the same as the conditions for putting up warning signs, reducing the speed limit, etc.