stratos stratos:
Would some of the disparity be caused by low population numbers?
Yes, and the lack of infrastructure. Fresh food, construction material, medical supplies etc. can only be brought into some northern communities in winter because there are no bridges across a land heavily populated by muskeg, lakes, and rivers. So you have to wait till they are frozen to bring in heavy trucks.
Shipping food by air means 4l (1 gallon) of fresh milk can cost $20, or $15 for a head of lettuce. And not every community can have an airport.