The EPA makes really tight emissions targets for vehicles under a certain size or the auto makers have to pay a fee iirc. Pretty sure they the medium sized stuff out of existance, an unfortunately I'm guessing the same fees would apply to imports too.
I think folks bought into SUVs since they were bigger & selfishly less likely to take more damage in a crash. As such, with SUV tanks everywhere, being a pedestrian or in a small car on the road on in an SUV’s trajectory can often lead to lethal injury.