Why do doctors think that one size fits all when it comes to treating health or psychological issues.

You're NOT wrong: There certainly are examples in Medicine (as in all professions) of folks who generalize far too broadly when trying to determine the cause of organic/non-organic dysfunction in their patients. I don't want to repeat what you've likely heard before but if you care to write more specifically about what's bothering you we may be able to forward ideas you've not heard yet. All the best

Not all doctors: Most doctors put people into diagnostic boxes & treat all with a given diagnosis with standard options. However, a foundational principle of holistic/integrative medicine is to see each patient as a unique individual and treat accordingly. Homeopathy is particularly individualized; 10 people with a given diagnosis are likely to be treated with 10 different remedies. Consider seeing a holistic doc!

Maybe you need to: Talk with your doc further. Mental illness treatments are anything but "cookie cutter." Most docs recommend meds, counseling , light therapy, exercise, dietary change, and good sleep hygiene. Co-existing illnesses need to be ruled out. It's trial and error and individualized care. Work with your doc and expect the same in return with layman explanations. If unhappy get 2nd opinion.