I've always wanted to write exactly this blog post. Keeping your salary confidential is great for big companies, but it benefits you in no way. You should be making what your coworkers make. If you make less, you're being fucked, plain and simple. The sooner you realize that, the sooner you can remedy the situation. Sadly, some people go their whole careers without doing so. FWIW, my first programming job only paid $…
If you're making less, you're possibly being fucked. You're possibly avoiding a layoff. If you're making more, I'm not sure how showing your salary data can help you personally.
Status, at least when you transition.
In investment banking, people would quickly discover what the top bonus was for their year and report it when they moved on to jobs in, for example, private equity. The banks saw it as symbiotic and would confirm inflated compensation. It made the ex-analysts get better jobs but it also made the firms look more generous, so it was seen as win-win.
It becomes an issue when next year's class expects the middle bonus to be last year's top bonus.