I was musing on this.
I recently needed some binoculars. The three brands that I looked at were Zeiss, Leica and Swarovski. The warranty on all of them is 10 years.
However...in the USA, the warranty on the same (exactly the same) models is lifetime.
Hypothetically, if you had a problem in 20 years time and they refused repair under warranty in NZ, could you argue in the dispute resolution process that the companies clearly accepted that a lifetime warranty was "reasonable" because that was exactly what they offered on identical products in the USA?