I don't think it's a USA VS Canada thing if you're referring to a buyer not understanding the nature of tariffs. Your average buyer whether it is someone from the Canada or the USA is not into ecommerce and whether it's the Canada Post Strike, or the Tariffs, they aren't really up to date on how they work. Most people here can barely grasp how it's going to work, myself included, and we're here everyday checking for information. I don't really look down on people if they have a question about the tariffs or don't understand exactly how shipping works, whether they are in the USA or Canada, I don't notice a difference.
As far as who "pays" the tariffs in a DDP type sale. It's the same argument that has been had here for years about who pays for "free shipping". The simplified version is that an item is worth what it is worth. Including shipping, taxes, tariffs, etc. If an item is worth $100 shipped, nobody from the USA is paying $100 with shipping+(whatever tariffs will be), because that will exceed the value of the item. At the same time, it's unlikely that a small time seller is going to eat the costs of the tariffs to make a sale, because on a $100 shipped item, most won't have the margin to do that. The result is, Canada to USA shipping is no longer viable for most items.
So it isn't relevant who physically pays it, or what order it is paid in, because regardless of whether the seller pays it and works the cost into the listing, or the cost isn't worked into the listing and the buyer pays it at the door, it's really still the seller who pays it via losing their margins, this is assuming they price their items at the peak of the market value. It's an input cost. The big takeaway is that it will possibly make selling anything to the USA unprofitable for Canadian retailers or eBay sellers because it will increase what they have to charge (directly or indirectly) to make the same amount of profit, so they simple won't sell to them. Large scale importing is a different discussion entirely.
Think of it like the cost of bubble mailers doubling. If I can sell a DVD for $15 ($10+$5 shipping) and that is the peak of what someone will pay. Then my bubble mailers go up from $1 to $2, and I cannot raise my price from $15 and still make a sale, so I drop the BIN to $9 and raise the shipping to $6, who is paying for that increase in price? On paper, the buyer is paying for the $1 increase in input costs, but I also had to lower my BIN to compensate. So really, I'm paying for it regardless of whether I eat the $1 increase in the BIN or assign it to the shipping cost.
That's a massive oversimpiflication, but tariffs will work the same way. It's an additional input cost. Someone has to pay it. Most people try to price things to get the most money possible, so they may not have room to raise their prices. The result will be a lot of sellers not shipping to the USA because it won't be viable with the increase costs to deliver a sale.
A lot of Canadian sellers could relate to the examples above, because those who weren't registered for GST saw their prices increase by 5 to 15 percent overnight when eBay had to begin collecting sales taxes. Even know the buyer was paying that tax, they may have had to lower their prices to compensate for the increase cost to the buyer. So in a scenario where their prices were set perfectly to make the most profit, even if the buyer pays the GST at the checkout screen, it's the seller who loses that money because they had to lower their BIN price to offset the added costs. That's a similar situation.
