Why aren't there any vin #s on Nissan / Infiniti bodyparts?
 

For replaceable parts such as, doors, bumpers, trunk, hood, etc etc. Why aren't there any vin numbers attached to it?

Makes it easier to tell if a part was replaced or not. I know all the Acuras have Vin stickers on most parts. Even the windows and windshield say Acura or Honda on it.