You know what? As a society, I don't think we have a data privacy problem, actually.
What we truly have is a
consent-respecting problem.
If, as a society and as individuals, we truly respected people's informed and freely given consent, we would not have problems with data privacy at all.
If we culturally improve our consent-respecting practices, we will inevitably understand better how to improve our privacy-respecting practices.
Ask first.
Give options.
Respect people's choices.
Never share without prior permission.