Quote from Havokki :

Its a Drift thing , so you can see the decals from the sidemirrors too when your going to the corner at 45 degree angle

Dude, the most important reason for reversing the decals/vinyls is the retain the structure and symmetry on both sides. Like if they didnt reverse them, it would clash, and don't look right. As when you put aftermarket decals in NFS UnderGround2, they don't get reversed, and screws up the look on one of the sides.