Although newer cars broadcast who they are through GPS (if anyone doubts that just check with automakers and car rental agencies, they know where you are) my best guess ties the RID and flight data storage to our Patriot Act.
It’s also an easy way to review flight data long after the fact for violations and follow on court cases. We might also consider at least one drone company, and likely other business, have been restructuring to collect and store data for various monetary purposes. Without an ID they have nothing to attribute collected data.