I've received roughly $3000 in rewards from my credit card usage over the past six years. Not a life-changing amount, but not completely insignificant, either. I think the biggest thing that I've lost is data privacy, but I would think that debit cards incur the same cost. I've never used any of the benefits like extra insurance/warranty, but it's nice to know they exist.
Chargebacks on debit cards are also much more painful than on credit.
Assuming NZ is like Europe, the are no rewards thanks to fees being low due to regulation. Chargebacks exist but are not as strongly defaulting on consumer side; to succeed, you need real proof of merchant not holding up their side.
It might be different in different countries, but in the US you do not pay additional to use a credit card. As long as you pay on time each month many credit cards have zero fees or interest. Rewards can range from 1-5 percent cash back, which does add up.
Now if you are making a larger point about credit cards increasing the general cost of goods across the board as merchants incur the cost and pass along to the consumer to maintain margin, sure, but that ship sailed a long time ago. The only reasonable reaction from the consumer is to leverage the convenience, protections, and float afforded by credit cards, while maximizing any rewards afforded by said cards.
Chargebacks on debit cards are also much more painful than on credit.