Because cars are not, in and of themselves, inherently deadly any more than a train or a boat or a plane are inherently deadly. The fatality component of a vehicle largely rests on operators and those who are around vehicles. If a pedestrian on their phone steps off the sidewalk onto the road and gets struck by a vehicle is that the vehicle's or even the driver's fault? Of course not, just like a pedestrian is not at fault if they are crossing the street properly and a driver ignores the crosswalk or red lights. This issue cannot be solved by simply putting more sensors in a car, drivers and pedestrians need to take responsibility for their actions and understand exactly what they are doing when they cross each-other's path.
You’re talking about humans, not machines. What you have control over is how cars and humans behave on impact. You don’t have control over what your neighbor does when they walk. Are you perfect? You never get distracted? For those unique scenarios, do you rather be hit by a lifted f350 with a madmax inspired bumper or you rather have a chance of surviving your mistake?
Of course I would like the consequences of a mistake to be minimal, but I also don't think drivers of large vehicles should automatically be assumed at fault and penalized just because they like to drive a large vehicle. Even the GHSA report's own solutions primarily focus on driver and pedestrian awareness programs and non-vehicle related solutions as opposed to more sensors in a car.
EDIT: They do suggest automatic braking solutions but even those can be hampered by inclement weather which large portions of the US are subject to. The last thing I want my car doing is locking up my brakes on a slippery road because it sensed a possible pedestrian.
