Theory vs practice.
In theory all these mechanisms help.
From experience a car with "emergency braking" would slam the breaks, jolting everone, while approaching a boom barrier - because the programmer did not think of such scenario. It would also detect benign metal surfaces (such as road signs, barriers along the road) and "help" with braking at higher speeds, creating risk o the road - because the sensors are still very limited and programmers trust them too much.
Yes, these get fixed, eventually. Even Tesla has a hard time figuring it out, other car logic might be even more behind.
The spiral comes from the fact that mechanisms to support faulty drivers breed even more faults in drivers. Lack of sensor warning becomes "everything is ok".
People get conditioned to "I stop car in a garage when my parking sensor starts beeping" so much that they just crash into the wall when there is no beep - the sensor failed, is disabled, or they drive a different car without sensors.
"GPS told me to drive into this river".