There are these things called building permits, zoning bylaws, public consultations, and environmental assessments that are required in Canada and the United States. There's also workplace safety, structural integrity, backlogs of maintenance, a completely different layout of cities, and a significant population difference that must be considered in North America. Even the 4.1 km Minatomirai line in Yokohama Japan (Another country associated with efficiency) took 11 years to build.
Vancouver got the Canada Line from proposal to construction in something like three years. Maybe it was 5 years. I can't remember... either way it was ridiculously fast.