The implication is that these are all foreign owners who have mega-bucks and aren't paying any taxes. Of course they miss the fact that granny has lived in her home for 40 years and does indeed have a low income and can't afford the tax. Basically it is just the NDP saying tax the rich and give us the money.
A similar issue came up ~ 20? years ago in Vancouver, when house prices first began to rise dramatically - Granny, on a fixed income (as if the rest of us aren't on a semi-fixed income) not being able to pay her property tax, and thus losing her house. The simple solution, implemented in some munis, was to defer property tax until the house was sold. That could be done in this case also.