This ask HN post surfaces a question I have often wondered but haven't found a logical answer to. Why do people not share their salary information more openly

This ask HN post surfaces a question I have often wondered but haven't found a logical answer to. Why do people not share their salary information more openly when it is beneficial for them. Most people know that sharing would help them negotiate better and in some cases take away the extreme amount of leverage the employer has due to comp being secretive. I will post this as a separate question to see what the hive mind thinks.