Or if your territory is made up partially of land the ownership of which isn't a pressing concern for anyone because it doesn't support a population and has few resources.

The western part of the boundary between U.S. and Canada is unusually straight, but I suppose that was an expedient agreement at a time when neither side wanted to go to war over it. Not that relations were totally peaceful or friendly.

Switzerland gets a honorary mention - the country might not be, but the people are total squares.