Heck even the older games like High Stakes weren't split. Prostreet wasn't split, Carbon wasn't split. It is a very different game from the original PS3/XBOX/PC version, and made by different developers too.
I dunno if this has been discussed before, but since i just noticed there are cars listed here from the PS2/Wii version of the game shouldn't the PS2/Wii version of NFS Undercover be in a separate entry?