How can I effectively handle situations where parents ask for pediatric advice but then choose to ignore it and make their own decisions?

Working in pediatrics for 40 years as an RN, I never did truly understand those parents who brought their child in for medical/nursing care, and then once they left the hospital or doctor's office, refused to follow through with the prescribed plan of care.
My first question to a parent in followup, or at the child's next visit was usually, "What made you decide not to follow the doctor or nurse's medical advice for your child after your child was last seen here? Then I'd listen to their reasoning or excuse.
Sometimes their excuses seemed reasonable...especially if it was related to lack of income and resources (which we could then help get them referred to a community system that could help take care of their child's financial needs for medical care.) Those were the easiest cases.
However, most of the time it was more like the parent made the decision to totally ignore the medical/nursing advice and instead took TOTAL control of their child's medical situation. BUT....when I next saw the child and their parent, I'd question their non-compliance. The parent usually responded by sharing his/her thinking/circumstances with me.Sometimes I understood (especially if it was financial need), other times I questioned the parent's medical background and the second guessing of their practitioner(s) plan of care. Other excuses offered by parents were: They felt they had the right to totally control their child's health care....but most acknowledged they DID NOT realize how detrimental their medical decision could effect their child's health.

When a parent consistently chooses to ignore medical and nursing advice/care, a doctor or nurse can refuse to continue to see the child because the parent's refusal could become detrimental to a child's full recovery. In many of those repeat cases, I was instructed by the doctor to confidentially report the parent to Children's Services and allow that agency to assess the parent's non-compliance with medical care.
It was often very challenging to be an advocate for kids and find the resources to help those kids who lived in homes where parents didn't take care of them.