[hjay]

From my limited understanding, it's not the best idea for companies who want to keep their costs to a minimum.

There are employees who are being underpaid and don't have many metrics to look at if they want a higher salary (win for the company). Then there's also that if companies make their employee's salaries public, there will be a more aggressive and obvious effort to poach employees from competition. Potential employees will benefit off of this war, while the companies will be just trying to one-up each other.

Not to say companies don't currently poach employees from competitors, but I think making those figures public would make that much more prevalent.