That's where you (and by some extension most computer science people) are completely off-base. You don't get to define what is private for me or what privacy means for me. It is a social construct. I have a select set of information that I do not want in the hands of a select group of people - THAT constitutes MY privacy.
That's not how it works. My privacy perception has nothing to do with another person's trust in me. And no I did not say I am volunteering ALL the information I am privy to - I did say that I have my boundaries. How I define those boundaries will obviously take into consideration what I think is a mutually understood contract between me and another person. But those boundaries vary from person to person and so it is futile to try to define someone else's privacy perception objectively.
> You don't get to define what is private for me or what privacy means for me
No, but I'm sure most people see privacy in a roughly similar way. You want control over what people know about you and your life, and control over who know it. This control is being taken away from us at every turn, no matter what we do online. Most people have no idea it's happening, but most of those who do, would prefer it.
You may be perfectly fine with losing your privacy, regardless of how you might personally want to define it, but most people aren't.