Any MDs out there that can explain this curious MD behavior?

For most MD's, their whole training is all about cure and doing whatever is necessary to cure a condition or a disease. And if it cannot be cured by medications then surgery. That is how medical training is done. Dementia - being a terminal disease - doesn't enable that. Most MD, unless they are gerontologists or work within a gerontology practice - like a neurologist often does - are totally not synched or trained to evaluate and treat any terminal diseases. So that plus the fact that there are many dementia's AND that diagnosis can only truly be done by an autopsy of the brain, makes them incapable of being able to ever adequately & definitely say and treat a dementia patient. Or do the paperwork to have them committed or declared incompetent.

You really need to have your elder evaluated and become a patient of a gerontology practice in order for them to get the best treatment plan for their specific type and stage of dementia and have them tested so that the gerontology
guys can have them declared incompetent and have the results to back it up. If family is squabbbling about $$ and control, a good lawyer will destroy easily a GP's credibility. You have to have a whole gerotology practice work up to do a incompetency if family is at odds on this.

Yeah I know if you are out in the boondocks, your care is limited. But you can find a practice affliated with a medical school or a free-standing gerontolgoy practice and get them into that and have the testing done so that the right meds can be prescribed it will be a godsend. By & large the dementia's on their own are a long decline and pretty manageable until the final phases with the proper medication. If they don;t have other diseases to any real extent like CHD or diabetes or a cancer and they have Lewy Body Dementia - like my mom does - they can be quite cognitive for ages although not competent. It could be a decade plus of diagnosed dementia till they are not capable of their ADL's at all.

I was just reading about this condition, and it seems that since there is no speciality, primary doctors are hesitant to make the diagnosis, in my opinion, they do not really understand the condition.

They don't want to be sued or get caught up in a family squabble. Too often the complaining relative is simply trying to get control of financial assets. The only way to get the person committed is when they are violent and the police (independent, third party, authority) have them hauled away to the county psych center.