Not sure what the policies are now, but around me, I can not go get any prescription for any back pain (have really needed it twice in the past 3 years). "Nope, go see your GP" (vs going to a walk-in clinic). The walk-ins around here all have signs on the front door saying "no prescriptions for oxycontin, etc"
Now... yes, I could try to "see my GP", which generally means waiting a few days. (and, I don't really have a GP anymore, because I can never get in to see him).
What's strange is that about... 6 years ago, going to one of the same clinics, my wife went with an eye problem. Specifically, she'd had a small piece of sand get in her eye, and it was really sort/irritated. Home flushing wasn't working, so we went to the clinic. As she was leaving, they asked if she felt she needed any pain medication. "Well, not really, but it's a bit sore, and I do have a headache". They gave her a script for 14 oxycontin on the spot. Same place last year would not even talk to me about pain medication ("go see your GP").