Why not alert to the driver???? BMW has collision detection system that makes a loud beep when it determines an imminent collision. The beep alerts the driver

Why not alert to the driver???? BMW has collision detection system that makes a loud beep when it determines an imminent collision. The beep alerts the driver regardless of false positives or false negatives. Its a simple solution which many cars have had for over 10 years. Why Uber engineers chose to not alert the driver is beyond me.