"Fairness" generally means one out of two things.

Either it's, basically, a signal of attitude -- to call something "fair" is to mean "I approve of it" -- or it is a rhetorical device in the sense of a weapon in an argument.

I think that people generally have gut ideas about what fairness entails, but they are fuzzy, bendable, and subject to manipulation, both by cultural norms and by specific propaganda/arguments.