Fair enough, to me it shouldn't matter. I may make more than someone else in my position because I command vast experience and capabilities, but may earn less than someone else who is better still than I am.
When I was a bit younger and more vindictive I'd like to try and talk to people about it. But most people don't want to tell anyone how much they make foe the same reason.
You have the right and should have the right to discuss your pay, but that doesn't mean that anyone who doesn't want to is a shill.