1. The Vancouver Special originated as a way to evade zoning regulations. The lower floor is 18" below grade which qualified it as a "basement" not counting towards floor area ratio calculations.
2. Once the design became widespread, the building permitting process was streamlined -- there was no need for a detailed review of plans if they were identical to previously approved homes.
3. These were fundamentally "cheap and fast" housing, and have a poor reputation not so much for their conformity as for the poor quality construction.
4. As a cost saving measure, Vancouver Specials often came with "unfinished basements". An entire generation of Vancouver homeowners learned to install drywall -- and often electrical and plumbing -- which further contributes to the poor quality of the construction.