Fedex and UPS are essentially small package outfits (yes very large mountains of small packages), but in the small package business you need to to flow your volume through the system, you need to make the system as "liquid" as possible to reach max efficiency and on-time service. It's better to have 2 or 3 or 4 smaller aircraft with staggered departures than one of these behemoths. If you're consolidating into a single aircraft, that means all those time sensitive packages have to camp out in the cavernous A380 until the last outbound package arrives at the ramp. Only then can the Big Plane fly on to the sorting center, be it Memphis or Louisville or wherever.
The problem is repeated when flying to destination cities. If the Memphis sort produces 400,000 pounds of small packages bound for Boston, it's best to send 100,000 on the first plane, then 100,000 more 30 minutes later and so forth, as the packages come out of the sort process. Waiting for the last package before launching the A380 would be terribly inefficient.
So why did FedEx and UPS order these planes? Fred Smith, the benevolent dictator of FedEx, loves aviation. He frequently flies the corporate jet himself and he actually poured $50 million into developing blimp freight in the early '80's. Smith the aviation nut just wanted very badly to see the monster fly. Now that he's had the joy of seeing the flying white elephant actually get off the ground, his dream has been realized. Hence the cancellation.
As for UPS, they pretty much operate in the FedEx slipstream, copying ( with talent ) everything FedEx does and that's what they did here, right down to the cancellation.
---ExFedExer
I always wondered why he never named it (even jokingly) as FredEx.
I understand that wake turbulance means that Air Traffic Control would have to grant a larger separation distance for the A380 -- something on the order of 50% more than any other 'heavy' IIRC. That wouldn't be too helpful to FEDEX either.