The infrastructure for the project is already built by the developer – water, sewer, power, roads. Mello-Roos is for “other”services like schools, fire, police. An expense, not a capital cost. Unless the Mella Roos developments get better schools, or better fire, or better police service, it is again disparate.
As to the arguement that “existing” residents have been paying longer, that would almost make sense if home sellers were refunded their payments and new owners of existing housing paid Mella Roos just like the buyers of new housing.
It is just another bull shit tax on new home buyers along with building permits, meter connection charges, and land offsets for “permission to build”. By the time most new homes are started, the builder is $100k into each housing start because of fees. This should offset the cost of a new fire house, but instead morons argue that any tax you know about is fair.