My friends and I regularly share how much we make, and even our 401k balances on any given day. We cover a fairly wide spectrum, with me hands down being the lowest of both categories, and it we're all fine with it too.

I mentioned elsewhere that there are many industries where transparency works, and the public sector is one of them. Your employer wants you to deliver deterministic output, and your pay reflects that.

That's less the case when you're constantly challenged with clean-sheet exercises where every single person will produce a different outcome. It doesn't even have to be a super senior job - think of someone writing newsletters. That channel can easily lead to 5% or more of total revenue, and different people will definitely produce different outcomes (just the subject line alone will have an impact). Why pay different people the same rate if their work leads to vastly different revenue?

The public sector also includes research universities, where the delivered output is certainly not deterministic. Salary transparency works there too. Maybe because the academia evaluates everyone's merits and achivements publicly all the time, so people are used to transparency.