Many fewer editing tools were released for GP3-2k than GP3. I would guess that this is because GP3-2k was only sold in Europe, and was nowhere near as popular, initially as GP3, for which many editing tools were released.
A few examples:
GP3-2k has no equivalent of:
GP3Edit (instead you have to install the multitude of files manually that GP3Edit does with a single click)
TeamLogo Creator (which is why there are pretty much no rotating logos in any addon GP3-2k teamart sets)
There is no GP3-2k car camera editor. The GP3 CarEditor can edit the GP3-2k car cameras that are the same as those in GP3, but it cannot edit GP3-2k's two additional car cameras.
GP3-2k will not read track record information from track dat files at all, unlike GP3, so you cannot have different track records shown in the game other than the one's originally in the game (unlike GP3, where you can have the game show different track records for different tracks in different years).