Signed, A Miata driver. If I ever get in a wreck, I'm guaranteed to lose, but at least I'll go out in style.
While this isn't a complete substitute for regulations that systematically fix issues causes by negative externalities, I'd rather live in a society where a lot of problems are avoided because my fellow citizens generally care about my well being, rather than one in which the government needs to intervene left and right.
In the same way, it isn't necessary to assume that he will cause harm, only that it increases the likelihood of causing harm. With a larger car, a driver is less able to see pedestrians, and children/shorter adults may be blocked from view entirely. Pedestrian injuries and deaths are on the rise in the US, opposite the general trend elsewhere. The primary difference is the prevalence of unnecessarily large cars in the US.
As long as SUVs exist on the road I feel like it’s a safety benefit for my family to have a similarly sized vehicle to protect my wife and child. I can’t control what others do but I can control what I do to keep my family safe.