The cause was easy enough to identify: Data parsed by Kuhls and her colleagues showed that drivers were speeding more, on highways and on surface streets, and plowing through intersections with an alarming frequency. Conversely, seatbelt use was down, resulting in thousands of injuries to unrestrained drivers and passengers. After a decade of steady decline, intoxicated-driving arrests had rebounded to near historic highs.
… The relationship between car size and injury rates is still being studied, but early research on the American appetite for horizon-blotting machinery points in precisely the direction you’d expect: The bigger the vehicle, the less visibility it affords, and the more destruction it can wreak.
More Than Just Bikes has a great video on how US automakers pushed the sale of gigantic trucks onto American consumers and how it’s caused a huge increase in vehicle related deaths.
tl;dw Trade wars and efficiency standards caused work trucks to be one of the few vehicles US automakers could make without needing to follow standards or have foreign competition. Automakers were incentivized to sell big inefficient trucks and SUVs to the average person and began to heavily market them as manly/cool/safe. What was once a niche vehicle is now 80% of US auto sales.
That’s been a thing for decades though.
In my area at least, I’ve seen a lot more aggression, and it seems to be backed up by data. 1H 2021 had the highest fatalities since 2006, and there seems to be a trend continuing to this day.