One reason against open salaries is that people would do a poor job in valuing other people's jobs and the whole idea of fair wages would be extremely subjectiv

One reason against open salaries is that people would do a poor job in valuing other people's jobs and the whole idea of fair wages would be extremely subjective. It's not uncommon the case where an employee is frustrated with his manager earning X times more than them while doing 2h lunch meetings every day. The manager might bring tremendous business value though.