Why Rehab For Teens Rarely Works

Here's a perfect idea that will probably never be implemented.
Having a Social Sciences degree and the gift of more than my share of life experience with addicted teens in rehab, here is my observation:
Teens admitted to rehab are immediately placed on other drugs than the ones they are addicted to, and then they are evaluated through the fog to determine a diagnosis, in order to continue them on a variety of "appropriate" meds for an indeterminate length of time.
My contention with this method is that no baseline determination can ever be indicated, therefore no diagnosis can be complete or appropriate. Mom and Dad bring children home with a cart full of interactive meds without any way of determining if any of them are working with or against each other or the diagnosis.
Here's my idea:
What if we just kept them off all meds for three or four days, feed them good food, let them sleep, apply urinalysis until all traces of the drug (or drugs) of choice are eliminated. In this way, a real determination about the addiction can emerge using talk therapy to present a plausible diagnosis.
Then, rather than dose them with a variety of meds that might or might not be making matters worse inside their little heads, they could walk away clear-headed with real tools and coping skills for handling the stress that precipitated the addiction.
Somebody needs to fix this system.