As far as I know (which isn't much) there are a whole range of infrastructure considerations. Runway side clearance splays have to be considered for the higher tail surface (than a 74) of a 380 on a taxiway. Many gates are designed for the 74. The extra wingspan of the 380 will intrude on the gates next door. Airlines still want a 45 minute turnaround. So the fuel will have to be pumped faster (bigger pumps, larger ground tanks, bigger reserves, etc.), a greater number of bags and people will have to be procesed in the same time, a greater quantity of sewerage will have to be removed and a larger amount of food and water will have to be loaded.