I thought that was odd, too. I've driven in both countries and they're very similar. Public transit is poor or unavailable for many outside of city cores and there's mad suburban sprawl. And the most aggressive drivers I've seen would actually be in Montreal.

I wonder if it could be cultural differences overall? Or maybe how much of Canada's population is so concentrated in just a couple of cities? Apart from the 401, most Canadian highways didn't feel nearly as backed as American ones, too. I've driven around San Francisco and Atlanta and they were both super packed highways with exit ramps constantly backed up for hundreds of meters. In Canada, the 401 is really the only highway I see that. As bad as inner city traffic can get, that's much lower speed.

But yeah, it's really hard to think of actual differences between the two. While the two countries do have overall cultural differences, I did not perceive a huge difference in driver selfishness or speeding. Contrary to internet memes, Canadians are usually very selfish drivers, too. Canada also is obsessed with oversized trucks. Ontario is the epitome of "just one more lane will fix all our problems" and train service is constantly underfunded (though I guess at least we do have the Go trains and buses, which seems to be more than can be said about many US metro areas).