At least from my experience, people who have emotional problems-know it.
Over 20 years as a practicing physician, I have seen numerous patients. I don't remember more than a handful of patients in which I felt they had some emotional issues, which they refused to acknowledge/were not aware of.

I do remember quite a few whose first sentence was-"It doesn't matter, you are not going to believe it any how". They all had experiences of being disbelieved by physicians, or it being implied (or more than implied) that they suffer from some psychological problem.

I did have many patients who knew they were anxious or depressed. Even today I saw a young woman who admitted she mostly needs reassurance because her mother was recently diagnosed with breast cancer. And it was very easy to give her this reassurance.

Depression can cause pain, fatigue and many other physical symptoms, but again I have seen very few patients with depression who refused to admit it or receive treatment for it.

I don't think my "mix" of patients is that much different from the average patients other physicians see. So, where are those 50% with "unexplained" diseases and ill-defined emotional problems. Why don't they come to my clinic? How do they "transform" to patients with an unusual response to a commonly used treatment? Less common presentation of a serious illness? Or even sometimes, admittedly, patients with symptoms I can not explain despite all my efforts.

Why do my patients clearly say they are anxious, or depressed or concerned. Why do they feel comfortable telling me so? Where are all those patients who are offended by being told that they have emotional problems?

Why do I see it as completely normal for a patient with a serious illness to feel scared, concerned, sad and a myriad of other emotional responses?

The irony is that I found myself as a patient who belongs to this group of non-existing patients (in my opinion). The irony was that I had an illness which would have intrigued me as a physician and would have sent me searching for hours to find clues, but did not do so for my treating physicians. The irony was that I could not protect myself from that approach, like I have done with my own patients.

I recently came across an e-mail I sent to a physician I consulted a few years ago (a leader in her field) I asked her what was the explanation for my near collapse during a very simple test. She never bothered to answer, as the results of those tests were normal. She only suggested that the "pain" from the test could have made me very anxious.
I later found that my response was the "marry walker phenomenon" which was a huge clue to the diagnosis of my illness. But, she never bothered to do an internet search to try and understand such an unusual and unexpected reaction.

So, you can easily see how "psychosomatic" explanations are created and how you can get those 50% of the patients.

My explanation for those diagnoses is a combination of ignorance and arrogance. Lack of curiosity and search for the truth.

And if my approach leads to missing a few patients who have "unexplained" symptoms which could successfully be treated with CBT and depriving them from that treatment-be it.