It is a business being a landlord. You must comply with the RTA and tax laws and ignorance is no excuse.the "mom and pop" landlords - it's an investment. And yes I hate that term. If it's a business, tax the income. Tax the gains. Where else can you run a business constantly at a loss and still make huge amounts of money?
Plus - Luxon and a huge number of these politicians have rentals. Massive conflict of interest. RESIGN!!!!
Any business can claim overheads as a business cost for tax purposes and mortgage interest costs had been a claimable overhead until Labour changed the law. It is no different to buying a digger or ten diggers with a 10% deposit, hiring them out and claiming the interest costs on the loan as an overhead.
Yields on rental properties are usually less than bank deposits, so on the face of it they are a crap investment. However, they can be profitable if they are held long term and you get rental and capital growth. This is not certain and varies widely. The last 10 years would have been the best since the 80's.