Well, our tourism taxes and levy's are already much lower than countries like the UK and Australia. There's plenty of room to increase those.
Doesn't stop a few million backpackers heading to Oz each year, and never will, when they have plans to work and just factor it into their travel/arrival setup costs. It's a right of passage for young kids from wealthier countries to travel enmasse for a year or so, and NZ & Aus will always remain 2 attractive destinations, for play & some work.
Plus you are often so caught up in the excitement & exhaustive planning of the trip itself, any nasty extra fees you encounter when you arrive you just take grudingly on the chin. You can't know everything, everywhere pre arrival.
Plus it's a long way from Frankfurt to NZ. You maybe never back, a once in a lifetime chance, before the set path of adult life intervenes. A $200 border tax, ain't going to deter even a 23 year old German with a bagful of Aussie dollars slogged picking mangoes. They want a holiday. They want to go to beautiful NZ. They'll just drop their drinking budget for a week or so.