No, it probably has more to do with your first point: speed. During the time it could take for a sonar (ultrasonic) sensor to send out a pulse and for it to re

No, it probably has more to do with your first point: speed. During the time it could take for a sonar (ultrasonic) sensor to send out a pulse and for it to return, the car may have travelled many feet depending on speed and road conditions. This would impact how long it would take to perform an evasive action and return to a safe state. That is just a guess, though - I haven't run the numbers to know if it is factual. Lidar, though, is much quicker, as you noted.