Speaking as someone who walks into Bow Cycle on a regular basis i think that there are several reasons for the difference.
The most important one IMO is that Calgary has undergone a massive population growth in a relatively short period of time. Lack of competition has allowed shops to become larger than they are in Vancouver.
Bow Cycle is not bankrolled by the motorcycle store any more - they are completely separate businesses and have been for the better part of a decade - coinciding with their growth. Bow Cycles owners are present on the shop floor or in the building in some capacity every day of the week.
You can still walk out of Bow Cycle empty handed, though sometimes you can be blown away by things like 20 sets of XTR trail brakes in stock and ready to go. Or that there are Zipp, Enve, Easton, Mavic and Shimano carbon wheels waiting for you to check them out.
For me the coolest thing about Bow is not the shop floor (which is massive), but that it is mirrored below by a basement of equal size; 63 staff on a early spring Tuesday - you better be able to get the help you need to find what you are looking for. An off site bike building operation that builds somewhere in the region of 5,000 bikes.
A big bike shop square footage is easy, Bow has an equally massive back room operation that keeps the whole thing running fairly smoothly which many people don't even realise is there.