It's a simple question of population density. If you look at the size of Scandinavian countries and their population density, they have roads to just about anywhere and you can pretty much access any piece of boreal forest in Scandinavia relatively easily. In Canada, in contrast, we have huge expenses for using helicopters to approach and measure plots that are in distant locations.
It's simply a question of population density and the resources available to do these kinds of inventories. One reason we invest heavily and continue to explore ways to improve our remote sensing satellite based approaches is so we can use data over larger geographic areas with finer spatial resolution to conduct these kinds of analyses and demonstrate how Canada's forest management is sustainable, what the impacts of climate change are and how fast forests recover from harvesting and wildfires, etc.