Do trucks and SUVs in the US even have emissions standards? I know they're exempt from emissions tests in many states which is part of the reason for their popularity.
Trucks weren't held to the same standards as cars, so manufacturers started making more carlike trucks to meet consumer demand for larger vehicles. The improved visibility and image of toughness and independence also helps drive truck and SUV sales.
Bad drivers driving huge cars through dense places are scary...
I think it's mostly related to the percentage of other vehicles that they can see over.
The only thing you absolutely don't want in snow is RWD.
In 1999, California enacted its LEV (low emissions vehicle) II regulations, which moved most pickup trucks and SUVs into the same regulatory scheme as passenger vehicles: https://www.arb.ca.gov/msprog/levprog/levii/factsht.pdf
Which is usually used with exhaust fluid: https://en.wikipedia.org/wiki/Diesel_exhaust_fluid
Somebody was blaming this on trucks, but I'm thinking this might be the opposite - their small cars as it was with VW because they don't have these sorts of systems in place.
But there are, of course, a lot of old pre-DEF heavy vehicles on the roads too that would not comply with modern emissions standards.
DPFs remove visible soot from diesel emissions, but their actual benefit for health is less clear. They don't trap the ultra-fine, PM2.5 invisible sooty particles which are the most dangerous because they can penetrate the lungs and enter the bloodstream. These particles are associated with increased risk of cardiovascular diseases and cancer.
DPFs also tend to break down after a few years of use. Often, they end up being (illegally) removed by owners who don't want to pay for an expensive replacement.