Mello roos don’t seem unfair to me, you are told up front what the cost is going to be and it doesn’t change over time. Its paid by all the people who buy into the development. So far as I know a Mello-Roos is just a bond issued by the developer to pay for infrastructure that the govt makes him build. Whats unfair about that.
Prop 13 is a totally different animal. It sets unfair taxation policies that favor one type of resident over another, even though all residents demand civic services.