Working in Wellington, I noticed more than 1/2 the jobs advertised are really not attainable.
I've seen it from both side over many years: as an applicant and based on asking my bosses about positions.
With government positions in particular, often they're internal candidates. Also often a position is created specifically with a person in mind.
HR is forced to do the bare minimum public advertisement.
They are also forced to interview a minimum number of people. It's a bit sadistic, since they are basically wasting every interviewer's time, and raising hopes, just so they can tick boxes on a form.
Sometimes these "vapor jobs" are not so easy to spot, but sometimes they are.
Indicators are only advertised on the agency's website, is very specific, "must have extensive experience with insert a custom written application only used by the same agency". Also a give-away is a very short deadlines, such as 2 weeks.
It's worth applying, and try your best, but don't your hopes up.
Usually job where someone has to pay to list, such as TradeMe and Seek, are a much better bet that they actually are real jobs, you can attain.
As a sidenote, if you're CV doesn't have a local mail address, your odds drop to near zero.
Remember in life, it's usually a numbers game: "you've got to be in, to win."