I suppose I take it as evidence that Dollar Stores aren't going extinct, but I'd be curious to hear an explanation of the stark difference.

Perhaps there are just some differences between the "hard discount" consumer crowds between the two countries? Even things as simple as the hangover from the US helicopter cash during the pandemic, which is causing a lot of negative comps in a lot of businesses. Or something more "core"...a little known trivia item is that the median Canadian is quite a lot richer than the median American in USD terms. The shapes of the income and wealth distribution curves are very different. Or it could come down to the fact that Canada is a smaller market, so many industries have much higher concentration, giving the leaders higher pricing power. Check out the price of a Canadian mobile subscription.

Incidentally, my lovely spouse is a keen dollar store aficionado in Canada. She reports that Dollarama is the go-to choice for the discerning dollar shopper. Dollar Tree locations are often grubby, though with wide variation, some being nice. This is a photo she took about three years ago at a Dollar Tree in Ontario, not GTA. http://stonewellfunds.com/DollarTreeShelves.jpg

Jim