So is the USA but it's still very expensive to live in NYC or SF. This isn't a Canada problem, it's a Toronto/Vancouver/Montreal problem (and their wider metropolitan areas), which together account for more than a third of the country's population.
> Why can’t Canada build more homes?
Partly due to idiotic zoning laws, partly due to the "missing middle" layer of the housing market, but mostly due to "investment properties" that sit empty and may as well not have been built at all.
> why can’t we ban foreigners from owning homes?
We sure could! Or just tax the hell out of it. But it wouldn't sit well with real estate developers and the politicians they've purchased.
It isn't just a Toronto/Vancover/Montreal problem. People in Halifax have seen rents and property prices soar.