To be fair, I never found opiates to ever eliminate pain, personally speaking. Opiates made me not care the pain was there.
I was in a pretty good scooter accident, broken jaw and everything. When the EMTs shot me up with morphine, I was still in every bit of pain that I was before, but it became this thing that I could acknowledge and put off to the side, which would no longer be screaming at me, dominating my thoughts. If I focused on it, I felt the broken bones, the bleeding, the cuts, etc. but If I just stared at the ceiling and thought of a happy place, it wasn't so bad anymore. It took the acuteness out of the pain, to the point where I asked if I could just go home after the shot, clearly high as a kite.
Opiates do this thing where they make pain bearable. They don't eliminate it, the way a topical anaesthetic might. It just rearranges the priories somehow, and puts the immediate and urgent nature that comes with pain on the back burner.