Earlier quoted context omitted.
Even when anonymous? --- I found this (relatively) old paper[1]. It mostly deals with reporting on government forms, but there is a little bit about sensitivity of the information reported. Singer, Von Thurn, and Miller (1995) have shown that assurances of confidentiality reduce nonresponse and/or increase the accuracy of responses to income questions and other sensitive survey topics. In addition, recent technologic…
Yes. It makes them feel good about themselves showing they have a higher salary than others. Even anonymously, would you want to report your under average salary? I mean you could, but would you take the effort to create a throwaway account just to do that? Probably not.
Glassdoor etc is nice but at least for SV most of the time just not accurate and in my experience on the lower limit. I'm not sure why but it could be that people just share more often when they start a job and not when they just don't care anymore after a few years while making a lot more at the same/next company.