I don't think this is true. I think people either don't understand it, or have a different comfort level than others. I work at a public library with people who struggle with basic information literacy, but they are very protective of their phone number. That's a piece of private information to them, despite how much safer it would keep them in the event their email account is compromised (or they inevitably forget their password when they arrive a week later to check their email for the first time). When I assist someone in setting up an email or Facebook account, I spend time to explain this problem to them.

People care, they just don't know.