I got a six-pack of Canadians last week for $5.99. Plus, they don't eat much, but poutine is just nasty.
I used to stop at a Tim Horton's/Wendy's in Squamish BC a lot when I'd go skiing.
The thing to understand is that Tim Horton's is a doughnut/coffee/soup place and Wendy's is a burger joint. If you go to the Wendy's side and eat burger, it's about the same, except it costs in Canadian dollars rather than US Dollars, and their ketchup tastes weird.
If you buy a doughnut, a bowl of soup and a coffee at Tim's, it's just naturally going to be substantially cheaper.
So, here's the scoop:
Coca Cola in Canada is far superior to the USA stuff. I drink coke in Canada. I don't drink soft drinks in the USA at all.
Canadian ketchup tastes like funky barbecue sauce.
All of this is because they use more sugar in CA than we do in the US. Maybe because sugar is cheaper there, like the previous posters said. I don't know.