Call Lexus and find out. Asking for opinions isn't necessarily going to answer the question. If people can't agree, then you should go to the source. www.lexus.com is your friend. Find a local dealership or email Lexus directly.
Lexus has been contacted several times, the answer varies but usually its because they felt that the non-clearcoated black both looked richer and resisted showing swirls better.
You do have to give them that, Lexus black looks fantastic when its all shined up.
It doesn't take a rocket scientist to figure out if your black Lexus is clear coated or not. Chances are if your car has any repaint on it you have a mix. Simply take some polish or cleaner/wax on a towel and rub it in an inconspicuous area and if the black transfers to the towel it is ss. Lexus began clear-coating the Black Onyx (paint code 202) in the 2000 model year. I know this because my 1999 GS was not and my 2000 LS was.