How do Canadians usually state this? In liters? Or maybe I should ask "litres."
Nothing is measured in gallons in Canada anymore (a big jug of milk is 4 litres), and I'm not at all sure that the average person would recognize the size of a gallon (except that paint cans are commonly called a "gallon" size, even when they're not quite that); similarly, all odometers and road signs have been in kilometres for longer than the average Canadian has been alive... but it has been traditional to express fuel economy in miles per gallon, and U.S. advertising and other media continue to show "MPG" numbers, so many Canadians discuss fuel economy in MPG. Unfortunately, due the difference in gallons, lots of them are using the wrong numbers (by 20%).
So, how would a typical Canadian express the size of a tank? Who knows - the average person doesn't measure volumes. Seriously... how many people can look at a tank and guess its volume? How many know how many litres or gallons or gallons

of water they use in a day?
You mean Escape is using our gallon?
The RV industry in North America is massively dominated by US products - largely from Indiana. Promotional material is made for the US market, and of course expresses sizes in US gallons (without designating "US", because that is reasonably assumed in the United States). It seems that in RV stuff the US gallon numbers are used here, without conversion or clarification. If someone were to convert for publication in Canada, it would make much more sense to convert to litres than to imperial gallons.
Where any consumer product in North America has a size in both litres and gallons, the gallons are typically US gallons: litres for Canada, US gallons for the US. Really funny is when the occasional manufacturer uses litres (and kilograms, metres, etc) in the french instructions for a product (the french is only included to satisfy Canadian requirements), and gallons (and pounds, inches, etc) in the english instructions. Hey, english-speaking Canadians use metric, too!
I think ETI is just publishing the numbers as listed in the specs from a US tank manufacturer, or even a Canadian manufacturer who prepares promotional material for the larger US market.