Capt. Condom, Air NZ is only 15 years behind QF (for example) with its draconian recruiting practices.
You have to understand that when you work for a subsidiary company the cards are stacked against you from the outset, compared to someone off the street when it comes to career progression. Primarily (especially if you're a captain in a subsidiary) it's the "double training" that gets you - the subsidiary has to train a replacement captain to fill your spot, and a replacement needs to be employed for the FO that got the upgrade. All those nasty training costs come off the bottom line of the group entity.
Therefore, it's more cost effective for the parent company to hire someone off the street than it is to do so from within the group.
As for success rate at interview - when I finished up doing it in 2008 for the QF group, it was about a 15% pass rate (in spite of one's best efforts to get the candidate through). The standard was not reduced to allow for lack of experience/poor training (key factor) or other factors.
Your best bet is to take your expertise outside of the AirNZ group in my opinion.