Less Hair
As I've said before, the problem with the A380 as a freighter is it can't carry the mass. Yes, huge volume, but due to the (relatively) low MZFW it's payload is limited to somewhere around 85-90 tons. That's less than a 777F, and way less than a 747F (the 747-8F is around 150 tons payload) - with much lower operating costs.
Yes, the A380 can carry that payload a long way, but the air cargo system isn't set up that way - the max leg lengths being around 4,000 miles. In short, although a 747F could go much further without refueling, it couldn't carry as much cargo - they'd rather carry more cargo and stop for gas midway than to make a 7,000 mile sector non-stop.