The same justification this cop gave will be the same one that will be used in the future to justify putting trackers on everyone’s cars.
I’m pretty sure that most cars made after about 2013 or so have trackers as well as “black boxes” that can tell the cops how fast you were going and what actions you took (changed radio stations, turned on the wipers, turned off the lights, accelerated, stepped on the brake, ... ) during the last 10 minutes or so before a crash.
For all or most new cars it’s already here. And it’s not just the government. I believe the car manufacturers are keeping tabs on you, too.