Companies fight tooth and nail to keep the market from encroaching on their decisions about worker pay. Why do you think there's a taboo or outright ban on talking about compensation at many companies?

I wonder how many companies have "friendly" no-poaching agreements with each other like what Apple, Google, and co had[1].

[1] https://www.theguardian.com/technology/2014/apr/24/apple-goo...