I was driving (~42 m/h) my Model 3 Tesla on a freeway and the traffic in front of me suddenly slowed down. The driver in front of me (she was a new driver with a new car) braked hard and came to a complete stop even though the traffic in front of her was moving. I ended up colliding with her as a result. I would have expected the Tesla Forward collision system or the Automatic Emergency Braking system to have activated and prevented this crash. Further, it seems Tesla brakes behave differently when it is fully charged as the engine braking does not engage. In fact the car seems to accelerate instead. If the Tesla Forward collision system and the AEB do not work and prevent such accidents, what is the point of having these systems?