The why's (devil) is in the details. Melbourne and Brisbane airports want to be the first home for 787-9's in the Australian flying habitat with having extended routes going to Dallas Texas. Perth wants the honors going to Europe. Qantas has 45 optioned 787-9's as its targeted expansion and can't start filling the order book until the airports get along with one another.
Qantas wants and needs to replace its aging 747-400's. The 787-9 is the right size however pride comes before the fall when airports are concerned. The solution is with Qantas and where they will base with its first 787-9's in Australia. The answer should be easy but the word pride and advertising is the sticking point. An easy answer is to have three 787-9's show up in Australia on the same day or in the same week. The first airport that actually can launch a flight wins pride award. The Australian government may offer a lottery for the honors of 787-9 acceptance and take this negotiation off the table and have Perth complete the 787-9 implementation plans as scheduled. Otherwise, Qantas may take its ball and go home if the opposing sides can't get along.