Because the bulk of the funding that's provided through it is through challenge grants. It's legislation in Congress in the United States that makes it available. That is publicly funded money from the U.S. government. The Government of Canada has to be involved in managing the whole program and be engaged in the science and all the background evaluation of it. The program is enabled by the governments of both countries. Then when the challenge grants are in there and the activities line up with NGOs or private individuals, you have this incentive for everyone to collaborate inside the framework.
On June 16th, 2015. See this statement in context.