If you built a 1000sf detached home in North America you'd have a hell of a time selling it later on outside of some very specific conditions as it'll not be much cheaper than a 1500-2000sf home.

Home costs do not scale proportionately with their square footage. For example you still have one refrigerator in most homes regardless of size, one front door, pay base flat fees for services and trades just to show up, permitting fees, etc.