In In re America West Airlines, Inc., 179 Ariz. 528, 531, 880 P.2d 1074, 1077 (1994), America West successfully challenged a statute taxing airline commuter planes at different rates based upon whether the taxpayer also owned large aircraft. Id. at 529, 880 P.2d at 1075. The Arizona Supreme Court found a violation of the Uniformity Clause, explaining that commuter aircraft must be taxed in the same manner because the property has "similar physical attributes and productiveness, and is used the same way and for the same purpose by owners in the same industry." Id. at 532-33, 880 P.2d at 1078-79. Importantly, the court explained that no Uniformity Clause violation exists when Arizona taxes identical property if it is used for different purposes. For example, the Arizona Legislature may place a Ford truck belonging to an airline in one tax class and an identical Ford truck belonging to a railroad company in another tax class and tax them at different rates. Id. at 532, 880 P.2d at 1078. This example emphasizes functionality and undercuts the emphasis by ADOR and the Counties on the physical component. In Uniformity Clause cases, form follows function. In America West, the Court was not concerned with the equipment used beyond that established by the statute, that the aircraft have a particular seating and payload capacity, to determine that the companies were using small commuter aircraft. The America West court in its determination did not rely upon the particular mechanics involved in the manufacture of the aircraft.