Plus, since property tax bills are only configured every two years now in Maricopa County, then the house's condition and selling price goes into figuring the amount of property taxes, does it not? So their tax bite is less due to the condition of the property, and that would be the base rate based on the selling price.
So unless they do major work requiring a building permit, then the County Assessor would not be coming by to reassess it, so from the outset their tax bills are lower and remain so unless and until they do any major work or repair requiring a building permit (and if they do it in stages, since it is based a great deal on the amount of the repair itself or if it impacts city or county services, they may never have to get a permit).
So it seems to me those in those historic districts have been getting a free ride on the backs of the other communities, as have most of those part-time retirees and such with second homes there that actually many times use more of the city services (such as emergency medical personnel) than other citizens.
So I can see giving seniors tax breaks if they are on Social Security and don't meet a certain threshhold due to illnesses or don't have a school district within their community such as Sun City, but not those that live in incorporated areas that are incorporated when they purchase the property and do have schools in their communities, and are able to well afford it, especially with many of those elderly individuals purchasing second homes from the East Coast and Canada.