You have 100 cars. 90 of them are factory colors. 9 of them are painted in different unique fluorescent colors, one of them is painted like the Batmobile. That one is very unique.
It means that among its peers, all of which are unique, one stands out.
The word ‘unique’ is defined as being ‘one of a kind’. It is from Latin, ‘unicus’, meaning one, sole, single. If you are referencing colours, EACH of the ten custom vehicle colours are unique (per your definition). Your Batmobile is referencing a vehicle that is unique amongst a RARE group of cars, vehicles with custom paint jobs.
Our edjumacashun system has dumbed down and softened words so as not to even give the pretence of offence to anyone or anything. The system loathes ‘absolute’ words in all things. Squishy liberals, as most edjumacators are, wish to avoid having to defend their POVs, so they attempt to change ‘absolutes’ to give them room to squirm.
Next time I meet a partially pregnant woman, I’ll pass on your example!;-)