California vs Montreal is cherry picking the data. You could easily say Chicago (cheap) vs Vancouver (not cheap).

The major economic tech centres in Canada are Toronto and less so, Vancouver. Montreal and Ottawa (because that's where Shopify is HQ'd) are the next biggest.

Toronto and Vancouver are hugely unaffordable when it comes to housing; Montreal and Ottawa are much more affordable.

On the flipside, Vancouver is apparently more expensive than anywhere in the US for housing and median salary is much lower than somewhere like New York City.

Moving just a few hours south to Seattle will give you a huge increase in salary and lower cost of living.

Montreal is a big city, so I concede you have a (partial?) point. I have heard horror stories about cost of living in Vancouver here on HN, as well as from people I met in real life.