One of the companies that has championed making salaries and equity public is Buffer. They have done a good job of not only explaining their formula, but also explaining their motivations, which are rooted in a basic cultural value called default to Transparency.
The pros of such system are that no one wonders if someone making the same contributions as they are is getting paid more. Since it is all public you can see. When you see, you can decide for yourself if the company is acting fairly or not. For the management, it means that they don’t have to deal with people trying to negotiate special salary deals which create equity issues with other employees.
The cons of such transparency are pretty much the same as the pro, it just all depends on whether you like the transparency and lack of flexibility:
If you are a highly paid employee everyone knows it and expects you to perform at a level equal to that. And if you are a low paid employee everyone knows that too. Some employees can feel embarrassed about having that info be public - they won’t come to work for such a company. And to significantly change your salary you might have to change your job position (this is often the case even in companies where salary is negotiated privately, but because that isn’t public employees might not realize that).
Similarly, management gets more flexibility in negotiating special cases when salary info is private. They may find that they can offer a special new hire candidate a salary much higher than typical for that position to counter another company’s offer for that candidate in a bidding war. (In the open salary case, with less flexibility and standardized formulas they might just lose that candidate). Management can also discover that some candidates are getting lower market offers, and save some money by offering that person a lower amount as well. That often is what perpetuates the gender and minority salary gap when salaries are based on past salaries.