This is because if you want to override the system in an emergency avoidance manuver you have the option to accelerate out of harms way. Example a truck is running straight at you from behind. If you need to press the gas to move your vehicle out of the way but it senses another car in front of you and applies the brakes you can't avoid.
It works for me and in the last years since I bought it, it saved me lots of times. The other day I put a skull on Toyota mark in the front, it looks great but the system is not functioning 😩
I would say we need more tests at higher speeds. Its nice that most systems can avoid accidents below 20 mph, but my daily commute involves speeds up to 50-55 mph. How well do these systems prevent or mitigate accidents at those speeds?