Same in Australia, I find myself having to adjust the cost of shipping almost every time i need to renew an item after a sale.
I am in Australia, and you are right. It is the remote areas. I sent an item out last week at a cost of $35.00 for shipping to one location, and $79.00 today for exactly the same item to a different location.
The problem is that when we list on Etsy, we do not know where our items are going to end up, so we can undercharge or overcharge on postage. As I mentioned earlier a difference of around $43 to ship the same item to different part of the country.