In short, they are trying to make shipping price more fair for the average customer (including those oversea, or in remote regions) by making shipping a bit more expensive where it is cheaper.
Charging people nearby a bit extra allows them to offset some of those costs.
They provided a few examples of backpacks shipping to remote regions in Canada (I forgot the name, sorry) custom upwards of hundreds of dollars, but they capped shipping price to 50/60$ for every customer.
Very happy to hear that (I live in Europe), but obviously you're probably not a fan of the idea as much as I am hahaha
I had to ship a laptop from me on Vancouver Island to my employer in Vancouver and it cost ~$50.
Shipping in the states is cheap. Shipping in Canada, even very short distances, is not.