Medical data is significantly more sensitive. Financial data says almost nothing about you other than what money you make and how you like to spend it.

Medical data discloses your sex, drinking, smoking, drug, and physical habits, along with any mental issues, genetic pre-dispositions, where you live, who your family are, where you have worked, etc. With only a little inference you can get financial information from a person's medical records.

TLDR;

• Financial records are designed to track accurate exchanges of money.

• Medical records are designed to keep an accurate representation of you. The goal is explicitly more personal.