IF it were available on one when backordering on the other, it would have been even more worth less than it is now. see, every registrar has a set amount of searches at the registry. If they cooperate they have more together. snapnames, pool, enom they have like each 10-20 registrars.. godaddy/wwd/bluerazor have 3 all in all. Given how big they are, you can understand their chance of getting your domain, especially as they don't know what domains are the toughest to get, is much smaller, than like snapnames that knows how many wants a domain, and can put more resources on getting that exact domain + they have a whole lot more registrars, + deals with network solution to even get the domain without it being deleted and given out to the public.
Now, this is really not godaddys fault. but if they want to compete with backorders, they need to find new ways, and co-operate with other registrars n the backorder business. Of course.. a lot of people don't know how it is and would think the backorders are the same. well, they are not..