In Aero Mayflower Transit Co. v. Board of Railroad Comm'rs, 332 U. S. 495 (1947), after disposing of the appellant's main claims, the Court in a footnote summarily rejected appellant's alternative claim that the minimum fee of $15 on gross receipts was unreasonable because it imposed a tax roughly 10 times greater than would be required if the percentage standard set forth in the statute (0.5% of gross operating revenues) were used. The Supreme Court observed that the "Federal Constitution does not require the state to elaborate a system of motor vehicle taxation which will reflect with exact precision every gradation in use. In return for the $15 fee appellant can do business grossing $3,000 per vehicle annually for operations on Montana roads. Appellant was not wronged by its failure to make the full use of the highways permitted." Id., at 506, n. 19. The disposition was thus based on the costs the State would encounter in collecting taxes for vehicles that earned less than $3,000 annually in Montana. The Supreme Court also emphasized the administrative impossibility of precise apportionment according to road use in Capitol Greyhound Lines v. Brice, 339 U. S. 542, 546 (1950). In that case the Supreme Court upheld a 2% tax on the fair market value of motor vehicles for the use of state highways as a rough approximation of use because of the administrative burden of applying a tax formula that would vary "with every factor affecting appropriate compensation for road use."