Canada

No, the number one cause is not building efficient high density transportation networks.

If you build efficient high density transportation networks like streetcars and subways, then people plan their lives around taking those forms of transportation, and thus will gravitate towards living near the stops and you naturally end up densifying housing around your network.

Endless suburban sprawl is caused by only building road networks so everyone plans their lives and housing around owning and using cars.

And at a fundamental level, corporations building out and then operating high density towers, is not building out a pleasant future to live in, it's building out a cyberpunk dystopia where the municipality expands vertically but cedes control of that expansion to exploitative corporations.

Canada has the existing space in our cities and towns and should be focused on turning more communities into Toronto's relatively dense 'streetcar suburbs', where you have a mix of lots of townhomes, semi-detached housing, and short apartment buildings, where people can for the most part actually fully own their property and building, while still supporting a relatively high density of housing. But we need to build out actual streetcar networks in cities other than Toronto for that to happen.