I personally wasn't really comparing the two, just because one character was worse doesn't take away from the flaws of the other.
Carter's attitude when he left rehab, being rude to the guy leaving, whining to Greene about having to do standard procedure drug tests, semi-relapsing and then not telling Weaver, etc etc It wasn't someone who left rehab with a sense of humility or gratitude or anything like that, he still had a massive chip on his shoulder and felt he was above being an 'addict'.
Granted, that scene with Chase seems to be the end of the arc to all intents and purposes? But that seemed a bit unrealistic to me, taking into account his behaviour and attitude throughout the first half of Season 7, that his addiction would never really come up again in a big way story-wise. Just one passive-aggressive interaction with Benton and he sees the light? Hmm. Obviously the writers felt they'd done enough with it.