It's "tract". And, no. Developers build developments that maximize their ROI and that means (beyond meeting zoning requirements) locating developments in the most appropriate place. If I'm a developer and I have a one square block tract of land in downtown Toronto, or near a subway or GO station I wouldn't consider building single detached homes because a: the land is too valuable and b: I can get much more ROI from building a condo tower, apartment tower, or mixed use commercial residential/commercial tower. Single family homes promote many goods, including stable neighbourhoods with low crime rates. Academics can stay in their ivory towers. People know where they'd prefer to live.