It is not generally true that physicians will treat people with somatic diseases well (or at all) if they personally believe symptoms are actually caused by psychological issues.
This is an unproductive, even dangerous thing to tell sufferers.
jessriedel, the consensus is that this is a physiological disease with an unknown mechanism. That's why it's an area of active research.
I don't know where you get the idea that the null hypothesis for the cause of any set of symptoms not explained by known biomarkers needs to be "psychosomatic disorder". That's not even wrong - it makes no sense.
The issue here is that you did some "brief googling" (your words) on a complicated, confusing, cutting-edge area of clinical research, and now feel competent to state your completely uninformed "null-hypothesis"...
ME/CFS is an under-researched, multi-system disease that affects people in a multitude of ways and is very hard to diagnose. There are no accepted bio-markers yet. There are, however, many well-respected researchers in the field, and more are beginning to enter it from all kinds of disciplines. Basically none of them think this is a psychosomatic illness. This is a good place to start for getting an overview of interesting current research: https://www.omf.ngo/the-end-mecfs-project-2/
Only on the very surface. Sleep apnea is relatively easy to test for. ME/CFS sufferers experience a kind of fatigue that is distinctly different from that caused by sleep deprivation. Look up PEM / PENE:
Co-founder of Gustav here. Thanks for the kind words :-) The 3% is of course a blended rate. There are positions/sectors where that would never fly, but others where 5% is feasible. Also we cover the full spectrum of what staffing agencies typically offer, including permanent placement type transactions. For those, our take-rate is closer to 20%.