The Jedi don't actually have uniforms. They have what they consider the traditional attire of the Jedi that many choose to wear as a symbol of their ongoing legacy, but Jedi robes are not mandatory. A great example of this would be Aayla Secura, whom I don't believe has ever
been depicted wearing traditional Jedi robes.
As for Carth, well, we only see him off-duty in the game, so naturally he is not in uniform.