The easy way is to make people who rent their houses out pay a business tax as if they were a retail store that the tenant is legislatively forbidden from being forced to pay as a line item. Being embedded in the rent it will acts to discourage the 'home as a rentable investment' to buyers because it will act like friction on a rotating wheel, removing momentum and things coast to a stop.
People who buy a house and live in it will not pay the tax. Those that rent part of their home as a BNB are hit by the full tax for each month of the year they rent out space, even if only 1 day = they pay a month's tax.
Sure, some will evade, but city/state access to BNB bookings and their books and payment methods will create a thicket of coercion that will make most comply. The BNB'ing of residences as well as the idea of a residence as an investment is indeed a cancer in our society, and it can easily be extended to multiple dwellings as that tax will reduce the investment potential of them.
You either do this or see the bulk of our society turned into tenants, as new home prices in Toronto are a million dollars or so and this is caused entirely by the investment and BNB potential run amock.
