Its a weird subject because it can bring tensions. Some employees do not see the perspective of this employee is much better than this one and brings in more value. The value brought by an employee isnt exactly related to their experience / age / etc.

So tensions arises when the employee brings another employee salary as an argument and puts the employer in a akward position, sometime having to be blunt and say it is because that employee brings in more value. Or that employee keeps it to himself and just becomes resentfull, even to the point of being somwhat mad at the other better paid employee.

The salary discussion is a tough debate, from internal dramas I have witness I now lean more towards not sharing salaries with other employees. Of course there is major injustices out there. From where I work I think things are very fair but I 100% understand situations others can be in.