They ignore the obvious economies of scale which cities enjoy.
True but the real question should then be why are people in Dublin paying higher property taxes than anyone else in the country? If there are economies of scale in the provision of services (and we all agree that there are) then should there not also be proportionately lower property taxes in higher density urban areas?
The thing that grates here is that house prices in Dublin impact more on local services in Leitrim than they do on services in Dublin.