Prior to the 1960s, Canada didn't have a national culture. We defined ourselves through our political institutions: a federal nation with a parliamentary form of government. Not a lot of patriotism. Then cultural Marxism became all the fad. And I don't mean that term in some sort of conspiratorial sense, I mean that in the Universities and among the state intellectuals, a post-WW2 national identity emerged that was undeniably socialist. Maybe because our political institutions had became socialist first, but I'm sure you could argue the chicken and the egg thing.
The first guy that really empathized this “Americans as individualists and Canadians as collectivists” was Seymour Martin Lipset, an American sociologist. He popularized the idea with his book The First New Nation. He compared Americans and Canadians using “pattern-variables”. Now anyone familiar with praxeology or Austrian economics or even libertarianism, know that this kind of categorization of human action is utterly unscientific. There are no constants in human action, you can't measure people like you would do to things in the natural world. Aside from superficial cultural differences and accents, there is no fundamental reason why Americans would be more individualist than Canadians.
Personally, having travelled extensively in both countries, meeting a bunch of different people from all walks of life, I can tell you first-hand that there are left-wing nuts who are apologists for Communist murderers in both America and Canada. Now that said, I do find Americans to be more entrepreneurial than Canadians. Canadians do seem more inclined to trust the government and rely on it. But we've also had this cultural Marxist notion that Canada is fundamentally more collectivist drilled into our brains since the 1960s. So this is multi-generational problem that has been created. This isn't inherently natural to Canada.
Lipset expanded his thesis that Canadians were less liberal, in the classical sense, than Americans in other publications such as: “Revolution and Counterrevolution: the United States and Canada” and also a book called Continental Divide. Lipset influenced Gad Horowitz, a political science professor at the University of Toronto. So you can see how this idea caught on among the Marxian academics. It's really a god-send, they're telling Canadians who they are. Horowitz wrote an influential piece of “Conservatism, Liberalism and Socialism in Canada: an Interpretation” in the Canadian Journal of Economics and Political Science in 1966.
Horowitz, of course being influenced by Marx, didn't rely on sociology but rather what we now refer to as the left-right paradigm. But more than that, Horowitz picked up on the Marxian idea that history is a set of stages moving toward communism. So the fact that Canadians were less classical liberal and more socialist meant we were further down the road than Americans and there was no going back. So you can really see how this idea developed that Canadians are more advanced or better than Americans. Because we care about community, universal health-care, gun control, etc. etc.
Horowitz also adapted his thesis from Louis Hartz, who also took that view that Canada was more collectivist than America and this was because of something ingrained into the culture of the people. With the publication of Horowitz' article, a whole industry was born. As H.D. Forbes, another professor from U of T, put its, “any overview of Canadian political thought or political culture must reckon with Horowitz' adaptation of Hartz.”
In the 1960s and even to this day, if you want to get published in a journal of political science or economics, you essentially need to conform to this notion that Canada is more collectivist than America. And you'll see this in the standard textbooks, The Roots of Disunity and Political Parties and Ideologies in Canada being the major works. But a third work, and this is probably the most famous one, amplified this notion and really made mainstream. The work I'm referring to is, of course, George Grant's Lament for a Nation.
Grant gives reasons why we should not be classically liberal and well, the rest is history. Lament for a Nation is still required reading in most political science or philosophy courses. Grant has been cast as a Canadian Idealist, which essentially means socialist. But he's more for a Tory socialist, and for some that might seem like an oxymoron, but if you think it through, Tories tend to be more about family traditions and social conservatism than for individual liberty and property rights. Grant was not a fan of laissez-faire capitalism.
So this is where the idea came from, it's a relatively new idea, it emerged in the 60s but it influences history before the 1960s. Most histories of Canada's origins and Confederation have been warped by this ideology but yet there is no sound basis for it. A better overview of Canada's origins would be any work by Janet Ajzenstat, or Peter J. Smith. I suggest picking up, Canada's Origins: Liberal, Tory, Or Republican? Which debunks Horowitz's original thesis. There is also The Canadian Founding: John Locke and Parliament, as well as The Once and Future Canadian Democracy both by Janet Ajzenstat. All three works reference Canada's Founding Debates, an indispensable resource that highlights the political philosophy of British North American politicians during the late 19th century.