Writer can't think of an explanation for secrecy about money and salaries.
> When I went to negotiate my first salaried job I had no idea how much to aim for. Was $30,000 a reasonable salary? $60,000? I realized then that everyone's aversion to talking about money had left me in the dark as to how the business world worked.
Writer inexplicably still can't think of a reason for secrecy about money and salary.
The reason is obvious -- keeping you in the dark pays off. The employer benefits from your ignorance. Other people in your approximate position, but who have the job you seek, benefit from your ignorance. Everyone benefits from your ignorance except you.
All I can say is, wait until you actually have some money and/or a salary. Then you'll understand.
> Why is everyone so hesitant to share their salaries and other financial information?
Because information has intrinsic value, and particular kinds of information have high intrinsic value. How many times have you read about a settlement between businesses in which the terms were sealed by a court order? Can you think of a reason why?