Until the middle of the last century (when I was young) physicians felt empowered, or in certain circumstances even impelled, to share medical information with each other and with the family and often with friends and co-workers while withholding that same information from the patient. Ignorance was considered a valid part of medical care and conspiracy by everyone who was not being treated was accepted as being in the best interest of the patient. A patient's preferences were not necessarily considered and a patient's demands to know everything might be resisted.
At the start of the 21st century, the concept of medical privacy has completely reversed this point of view (at least in law and public opinion, if not universally in actual practice). Today, patients have an absolute right to know everything about their diagnosis, treatment, and prognosis. It remains acceptable for physicians to share with other medical professionals but only if both are involved in the care of the patient. Family, however, and certainly mere friends, are to be excluded unless --and sometimes even if -- the patient desires them to be informed.
In financial matters, the shift has not been as dramatic or complete, but law and opinion has turned against businesses sharing details about their clients and customers except with some sort of informed consent by the person whose finances are being judged. Employers still purchase credit reports on employees and candidates, but the public mood seems to be turning against the practice and individuals already have the right to review those reports (but not yet to know who else is reviewing them).
Similarly, it was common practice to request secret evaluations of any person being considered for employment, grants, or honors. The person whose opinion was solicited was often admonished, "Do not share your recommendation with the candidate." It was to be a secret shared with anyone except the person most affected. Today, letters of recommendation are typically shared with the individual affected and past employers -- facing possible litigation -- have largely stopped providing any kind of evaluation at all.
In all of these examples, there has been a significant shift in who is permitted to receive private information. It is worth noting, however, that the content considered to be private has not changed nearly as much. Diagnosis, treatment, and prognosis were and still are considered private to the patient. The difference is whether patients or those surrounding the patients have access to that information. Somebody decides who can see information about your income, expenses, and debts; it wasn't and isn't simply made public. What is changing is who makes the decision.
Thus the current changes in the area of privacy are not so much changing the definition of privacy or of what information is private but rather relate to empowerment and who has the power to decide how and with whom the private information is to be shared.