It doesn’t. The Toronto and Montreal metro areas are about twice the density of the DC metro area (14,000 people per square mile in weighted terms, versus under 7,000). But about 20% of DC area commuters take transit, versus 22-23% in Toronto and Montreal. (Remember, we’re talking about the whole metro area—in all three places, most people don’t live in the city proper.) In all three places, roughly 70% of people drive to work.