I think a change that’s very easy to make, will have some impact, and would draw far less pushback than more extreme measures would be to have landlords forced to report all of their costs, earnings and capital gains related to their property either directly to the tenant(s) or on a publicly accessible register on a regular basis. Prospective tenants would be armed with more information and would be able to know if their landlords are bullshitting with related to costs. Companies could create lists where they rank landlords based on how much profit they leech from their tenants. People would be able to know if they’re renting from someone who owns one additional property or fifty-three.
It won’t make a massive difference, but it’s a low-cost and fairly easily implementable measure that could be taken as part of a broader suite of measures.