The Reason Why Are Trucks Getting Bigger

"Bigger trucks pose a greater hazard to pedestrians and smaller vehicles"

It's an arms race.

I used to live near a couple who were both doctors in the ER and they both drive the biggest trucks that they could find because they saw that people in large trucks tended to be fare better in accidents.

I have a small sedan for myself and a smallish SUV for my wife and kids. I feel pressure to upgrade both to something larger.

I looked into this in detail one time and my fermi estimate was that, if we banned trucks entirely, it might optimistically save like 40 pedestrians a year. It's clearly not worth bothering, just on the grounds that it would be politically expensive, and it's also pretty clearly not utilitarian either.