meta: people who want to know salaries of their peers and demand equality have a bit a wrong view on companies.
Companies are anything but not about equality, playing fair or being nice to employees. Paying your staff different salaries is crucial and key to run a stable organization. Most won't get why different salaries on the same level create a stable organization, it's complex and would need an extensive/scientific article.
An organization's owner's goal is not to make the individual one happy but rather keeping the entire org on a good track. This involves keeping salaries inequal. Maybe some of you have an educated guess on why inequality creates downright stability.