Surprise, surprise: National, the landlord's party, opposes rental warrants of fitness, spouting the usual bullshit about how they'll drive up rents and see people sleeping in cars. Of course, what they're really worried about is that landleeches (like their very own Jian Yang, and other National MPs before him), will no longer be able to profit by renting out cold, damp, and unsafe homes. This is about them privileging their own profits over people's health.
But think about it: in virtually every other transaction, the goods you buy or rent are required to be of "acceptable quality": fit for purpose, free from defects, durable and above all, safe. And if its not, they're required to fix it. If its not safe, the government can impose safety standards, recall it, or even prohibit its sale.
Or, to put it another way: shops can't sell you products which are fundamentally unsafe or unfit for New Zealand conditions. So why do we let landlords do it?
Rental warrants-of-fitness are just basic product standards, and we shouldn't allow landlords to escape something so fundamental, especially when it imposes costs on the rest of society. Instead, houses should be regulated like any other product. And if landleeches don't like a warrant-of-fitness scheme, there's a much simpler solution: amend the definition of "goods" and "trade" in the Consumer Guarantees Act to apply to rental properties and landlords. Then let the Commerce Commission sort them out.