"Inequality" is a bad rallying cry because no two people are equal, and few would like to be equal to someone else. So what people mean by "inequality" is always something else, and varies in meaning from person to person. Even if you choose something concrete, like "equality of income", few really mean that an 18 year old should have the same income as a 45 year old.

Ordinarily a meaningless word is great for a rallying cry, but things like "equal" and "fair" are just too meaningless.