Bruce gurgled happily, sounding much like they
were saying:

Perhaps the government decided it was worth it for the reduction in
hassle for the owners and less beaurocracy being required if the plate
stays with the car for its entire life.

There's absolutely no reason why the old style plate couldn't stay
with the car for its entire life.

Providing that car stayed registered within the same dept.

No, it would work exactly like our own system, where the car is
registered in the "Département" it is purchased in, and retains that
numberplate for its whole life. I'm sorry if you can't understand this,
because it is about as clear as I can make it.

Sorry, I mis-read and thought you were describing as it currently works.
In that case, I agree - but it'd be as basically irrelevant as the
geographical identifier is on UK plates.