Let's try to remember that people with medically unexplained pain will be experiencing real, actual pain.
They're not inventing the pain. We can put them through fMRI and see the same bits of the brain light up.
The public have 3 incorrect beliefs about pain treatment.
1) Opioids work
2) The only acceptable outcome for pain treatment is elimination of all pain
3) Pain is either real (with a physical cause) or not real (psychologic, or made up).
It seems plenty of doctors believe (3) too.
Patients reject treatments that don't fit these beliefs.
As you know opioids are a good choice for some types of pain, but they're a poor choice for others. The patient will end up with an opioid addiction, and all the side effects from the opioid meds, and they'll still be in pain because they've got a tolerance to the meds.
So pain treatment now will try to eliminate pain if possible, but some people that's just not possible, and so HCPs will look at function. How well can the person live their life, even if they're in pain?
This leads to a multi-disciplinary approach to pain management, including physiotherapy but also importantly including a psychological treatment.
If this was a standard approach for all pain, obviously being tailored for different types of pain, patients would be less likely to reject it. Your "nuts" (a fucking horrible way to describe patients and incompatible with a professional registration in England) would be less likely to reject psychological treatments for pain if they knew that it was also being offered to cancer patients.