I think the majority of Canada's GWVR limits can be a factor; i.e. outside of Ontario it's less than half what the US limit is for a standard license.

I think also the lower number of lanes on routes like the 401 help, usually[0].

Even though it's been a while, every drive in Canada just felt more leisurely. Speed limits in general are lower, there's more stop signs where they should be.

[0] - Except when a whiskey truck tips over and it's now a 2 hour delay to the next exit...