AFAIK NZ has no more 24 hour supermakets. I remember brisbane used to, but a quick google search shows that might not be true anymore?
When I was staying in South Bank, restaurants were regularly open until 9:30/10pm. Finding places like that in christchurch is much harder, outside of thursday/friday/saturday. Auckland might be better, but it's been a while since I've stayed there.
TBH, maybe it's not that brisbane is good for late night stuff, maybe it's just that NZ is even worse.
They're not different to the consumer. Either way they're a surcharge to the store price of the item, and most places in the world include it on the sticker.