The correct answer is - the influence of U.S. entertainment and news sources.
Most of the Canadians live right next to the border with the United States. The travel and communication and easy and without any problem, and also the sharing of the information. In Canada there's lot of US entertainment shows, music, as well as all the important news from their neighbors, so the Canadians are relatively well informed about their neighbors and their culture.
The Americans, on the other side, are much more closed culturally, and almost exclusively everything in the entertainment and the news is US dominated by far, so we can even say that the Americans are very ignorant from that perspective. That has contributed to the majority of the population being relatively clueless about the culture of their Canadian neighbors.
