I have a family member with mental illness. A difference between treatment for mental illness and treatment for other diseases is how open-ended it is. You won't give someone chemotherapy forever, but there isn't a clear endpoint for psychotherapy, and patients may not find psychotherapy to be unpleasant and not be motivated to end it. Mandating insurance coverage inevitably raises premiums and causes some people or employers to drop insurance.
With some apology for rewriting the abysmal headline
> It keeps people with schizophrenia in school and on the job. Why won't insurance pay?