Highly likely a lot of it is simply older cars without safety features we consider basic these days (like side air bags) being phased out. Very few people driving cars from the 80s or earlier these days.

You can probably thank Ralph Nader for a lot of it, honestly.

motor vehicle deaths have always trended down, cars just keep getting safer

https://en.wikipedia.org/wiki/Motor_vehicle_fatality_rate_in...

A lot of improvements in vehicle safety were made between 1990ish and 2005ish. Around 2004-14 period the older cars that teenagers drive would have started being models with airbags and ABS. Neither of these have much impact on fatalities among "average drivers" but young driver's propensity to crash into things at very high speed and propensity to load more people than seat-belts into vehicles plays right into the use cases where these technologies will save the most lives. Cars from the mid '00s on up will also have much stiffer cabins because of a bunch of rollover and side impact rule changes that took effect around then.

Car were safer and safer, ABS and stuff helped, Also the whole world started doing crash tests to help protect the drivers and passengers.

Note that the trend continued past 2014 in Europe (stabilizing now). Two differences:

- Less SUVs/light truck on the road in Europe (it's changing)

- crash tests in Europe test small cars against SUVs, SUVs against trucks... All different combinations. If your utility vehicle / SUV doesn't perform well on those crash tests, you can't sell it (hence no F-150).

I’m curious if it could be safety technology improvements and child car seats?