I'm not sure the team knew about Reid's problem
Ok so we talk about how the team didn't do anything for months about Reid's dilaudid addiction, but we're working under the assumption that the team had all the clues we have.
But I rewatched Revelations recently - and he's never given the drugs on camera. I checked the episode - Raphael is the only one who puts the camera on. Tobias gives him drugs before the first broadcast, the second time is after it's turned off, and the third time is right before Raphael takes him outside to dig his grave.
Which means that the team don't know about that. Surely the medics at a hospital would know, but that's also a thing I can easily see him asking them to keep private, which is his right.
And this explains why they never properly notice or do anything. They see his bad mood, they know "somethings going on with him" (Gideon E18), but while it might fit the symptoms of drug addiction, they also know he's suffering from PTSD (his flashbacks, which is essentially what he's self medicating for) and would assume that to be the cause of his odd behaviour.
Besides the existence of the drugs as what Tobias took, there is no reason for the team to assume that a drug addiction is the cause of his problems. They wouldn't jump to that, because they know Reid and have the unconscious bias that he would never do something like that
Additionally, every talk he gets from Morgan and Gideon are all about his ability to keep doing his job despite the trauma he went through, not about anything else. Which is one of the things Reid is going through, with his flashbacks and missing the plane just to see if he could, but despite Gideon stating he knows something is going on, he clearly doesn't know anything about the drugs, which are Reid's second problem in this case.
Of course they do eventually work it out, since it's an open secret in later seasons. But I'm not sure they knew during it.
(Also worth noting that dilaudid can be taken in pill form, and with the many risks of injecting stuff into his veins, it's lively that Reid would have switched to that. Which means he doesn't even have to hide away for too long to take it, he can just swallow a pill every so often, and there's no physical signs like track marks)