Until the government changes the rules again to suit itself there are only three ways to get to annual leave monies:
1) If you have more than two (three?) weeks accrued you can on your employers agreement , opt to have 1 weeks worth a year “bought out” by your employer. This is relative recent legislation (ie in last 20 years). Not all employers have the cashflow for this so there is much more leeway for employers to say no.
2) As you have mentioned, resign, which technically means you go on leave (thus receiving all your days leave) before the end of your contract.
3) Take annual leave. This means you get your annual leave amount…. but you get no advantage from the subsidy.
The last two options have firmly been root in NZ Employment law for a long time, firstly to stop employers forcing people to stay labouring and using unwritten bias to ensure any that actually took a break would be penalised. By locking the inability to redeem the days for cash stopped that occurring.
The other reason is the government of the day (Edwardian times) decided politically for economic reasons that peoples’ health was suffering because of no breaks, and they decided on “weekends” and eventually 40 hour work week, so a leisure market could be invented. Many poorer people didn’t have the money for such malarkey, but “to stop their employers taking advantage of them” it got made into law so applied to everyone (Liberalists will accept anything as long as it affects everyone – One Law, everything is fair if neither rich man or poor can steal bread or live under a bridge). And it has been locked into law, and Union reinforced, that “Employees requirement two (then three, and now four) weeks off in leave every year for physical, emotional, and psychological recovery”. Thus being a political move, based on national economic interference by government, it was enshrined rigidly into policy and legal requirements.
Not a lawyer, not qualified to give legal advice. This is general information and my personal opinion, offered to help inform and entertain. For any particular legal matter you will need to contact a local specialist in your jurisdiction with skill and certification in the relevant speciality of law that pertains to your particular situation.