I have a Air NZ Airpoints card which doubles as a Flybuys card (Flybuys are automatically converted to Air Points). I noticed on the Air NZ website points can be incurred on a Westpac Mastercard debit card and I confirmed this at the Westpac site (1)
All banks offer a credit card which incurs rewards but not everyone wants a credit card. I use Visa Debit very often. I think this would be a winner for BNZ and generate additional profit through interchange fees.