Well that is fairly sucky. I guess for the first time since 2013 I am considering adding a first class international flat envelope option to shipping (although it would have to be manual as Etsy Shipping Labels doesn't do it, and hopefully I won't have to get rid of Calculated Shipping to add it).
Edit: I have to get rid of Calculated Shipping to add it, and it won't work right for some things anyway, as it has to be a uniform thickness. So I am considering replacing Calculated Shipping with manual values, including the flat envelope option (which is something like $2.50 instead of $9 and requires no customs form), on the one listing it will work well for - the uncut listing, which is uniform thickness as it's just flat sheets of labels.
But I'll have to start convoing Canadians and telling them this when they order, or something, which is a bit of a PITA.
On the other hand I prefer selling uncut labels anyway, so maybe I'll sell more of those to Canadians now :)
Oh well, at least things always *get* to Canada. Been having a bear of a time with non-deliveries in Europe recently.