I once had to threaten to resign from a job (in the EU, pre-Data Protection Act) over the data handling of evidence of one of the things in your comment.

I think this has been something people have had an instinct about forever, and the only reason I had to threaten to quit was because of a misunderstanding of the level of data safety involved; put simply it was not common knowledge that socket connections could be snooped and that targeting a popular service would be easy for a malicious person to do. (This was before SSL was efficient or easy to manage, and in the days when only payment screens were encrypted).

Once the message was across, everyone's objectives were aligned again.

Health information is deeply private because disease is entangled with shame/weakness/vulnerability/taboo/intimacy.