[jiayo]

Exactly. There's lots of intense density (50+ storey residential buildings) in a small geographic area, but for the other 75% of the land area of Toronto, it has been illegal to build even a 4-plex; zoning allows single family housing only. If you look at neighborhoods in Montreal where there are blocks upon blocks of 4-6 storey low-rise, that type of construction simply doesn't exist in Toronto.

Some good search terms for this topic are "the yellowbelt"[1] and "the missing middle"[2].

[1]: http://www.mapto.ca/maps/2017/3/4/the-yellow-belt

[2]: https://99percentinvisible.org/episode/the-missing-middle/