You seem to be entirely missing my point. Methamphetamine, like oxycodone, is legal, right now, in the US. Here it is:

https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/00...

I don’t, and never have, seen posters in doctors’ offices suggesting that patients get ahead of their symptoms (of hunger? sleepiness? distraction?) by taking prescription meth. And I’ve never heard any suggestion that the high incidence of methamphetamine is caused by its legality.