> But the officials can’t change the fact that there is only so much land to go around and a disproportionate number of people strongly desire a detached house.
That may be true, but the housing cost crisis extends beyond detached houses. We need more apartments, condos, townhouses, etc. Not just nice detached houses. Prices should get lower in all of those categories. Even condos in towers have grown much, much more expensive.
> You could potentially tear down some mansions in rich neighborhoods to build two or three houses and that might help slightly at the margins.
Most of the land in Toronto is tied up with single family detached housing. Why not replace some of these with small apartment buildings, brownstones, and townhouses especially when near transit, or villages? I live in a large house that is a 10 minute walk to transit and two major strips of retail. This neighborhood is mostly detached houses and duplexes. Why not allow for double, triple, or quadruple the density with townhouses or small apartment buildings? If done at scale, across the city, this could absolutely make a huge difference, in terms of the availability of housing.
In terms of mansions, why not spend a few hours walking around Forest Hill. You'll probably need more time, though, if you want to see them all. It's a beautiful neighborhood. And very large.
> The problem is a handful of cities are winners and everywhere else is losing.
There are other nice cities that are growing -- and the housing prices are growing exponentially there as well. (For example, Waterloo and Victoria.) Everywhere else is definitely not losing, though I agree that there should be more thriving cities in Canada, that is also a daunting task. Frankly, it's also a lot more daunting than changing the zoning to allow for medium density in single-family neighborhoods.
The bottom line, though, is that you're right about what officials can't change. They can't change the amount of land available, but they certainly can and should change the amount of development that is allowed on it. The current plan is simply not working. Something needs to change. My proposal is to allow medium density development; I don't see a better alternative.