If I understand your question, you are asking why it's considered disrespectful to ask what someone's salary is... some folks consider that information to be personal as they place a great deal of personal stock and self esteem in what their rate of pay happens to be and they're afraid that they aren't making enough money to be respected. Many people here seem to believe that the person who dies owning the most possessions or has the most money wins some sort of prize. It is a sad and shallow culture.
It's my business and my business only, same as yours. I would never dream of asking someone how much they make. As far as stinkfoots comment, He who dies with the most toys is still dead.
If someone asked me that I'd reply with the answer.. I take no pride in what little money I make, nor do I care
Even I dont like if someone asked me about my salary package as they don't have to do anything with it.