re: Why is talking about salary a taboo?

Generally speaking those that make more are more comfortable discussing income, obviously. As somebody that has been privy to salary info at many large companies, I can say that it's not normally a good situation knowing what co-workers or friends make. Many reasons for that.

I can say that as a finance guy doing work with engineering companies, I loathe knowing what some engineers make. should've done engineering

On a personal level, it's the jones' mentality that makes it tough. I make more than most think due to my modest home spending, and I'm ok with that, but I just don't think it's anybody's business, and I'd rather people assume I don't have money.