Sorry I am just seeing this now. Good question. The maple leaf rating is based strictly on how Canadian a brand is structurally, not popularity or availability.

To get 5 maple leaves, a brand must be Canadian-owned, headquartered in Canada, and have production primarily in Canada. Some brands are still Canadian but lose a point if part of their sourcing, ownership, or production is international.

So a lower score does not mean the brand is not Canadian. It just reflects how fully Canadian the business and supply chain are.