Re hard braking: Smooth driving may be a nice-to-have, rather than an clear indicator. Or, to put it another way, if there is a useful signal in apps that score

Re hard braking: Smooth driving may be a nice-to-have, rather than an clear indicator. Or, to put it another way, if there is a useful signal in apps that score driving smoothness and lack of distraction from phone calls and texts, extracting that signal from the noise of whether the driver frequents dangerous roads, drives at night, drives fatigued, intoxicated, is using a second mobile device, in bad weather, etc. isn't easy. Or, to put it yet another way, the real signal isn't in the score provided to the driver, it may be something the driver would consider unfair and outside their control in many cases. These apps influence drivers to drive more smoothly, which is useful for ride hailing since it improves the perceived quality of the ride, but that's much less directly connected to safety.