For the first time, the US is aiming to increase safety of people *outside* the vehicle.
This encourages active transportation.
Also, smaller vehicles use less energy.
"If enacted, automakers will have to test their vehicles using crash test dummies representing adult and child pedestrians for the first time. NHTSA says the changes could save up to 67 lives every year."
[Edit to add] This covers only head injuries.
https://www.theverge.com/2024/9/10/24241047/nhtsa-rule-pedestrian-safety-fmvss-suv-truck-designd