That's true: the Māori population of the South Island was (and remains) generally sparser than in the North, traditionally more dependent on a hunter-gatherer lifestyle in the old days than in the more settled North, though still sufficient to account for many authentic Māori place names (though apparently not Punakāiki, then). And yes, these days it can be a bit of a shock to get on the plane in a Hawai'ian shirt in Auckland and then get off at Queenstown in the South Island after jetting poleward for the best part of two hours. New Zealand is often described as a small country, but it is not that small, and there are huge regional differences.