Those living in Southern Ontario stream down to Buffalo to engage in "cross-border shopping". The reasons are many, but the most commonly cited are lower prices and a wider variety of goods.
Still, when I've taken trips to Toronto, I've noticed brands of products that are very common which are either unavailable in the US or else very rare. One that comes to mind are Bata sneakers; I've never seen them for sale in the US, but they're as common north of the border as ... oh, a second-tier brand like Adidas or Reebok in the US. It's a brand that is very international in scope, too, except for the US.
Of course, there's Cuban cigars and other products that are unavailable in the US. Until a decade or so ago, Ikea stores were far less common in the US than in Canada and other Western nations, and they're still not very widespread here; they're mainly confined to the largest metropolitan areas, and along the coasts. Cities of a size that easily support one or more Ikea stores in Europe, Australia or Canada are Ikea-less here, and many will likely never see an Ikea. (Ikea representatives told officials from the City of Buffalo that they'll never open a store in the Buffalo area, period, even though they're in similarly sized or smaller metro areas elsewhere such as Hamilton and Adelaide.) Many vehicle brands are unavailable in the US; SEAT, Skoda, Peugeot, Renault, Citroen, Proton, Fiat, Lancia and many others.
What other brands can you think of that have an international presence, but which are rare or nonexistent in the US?