Trade and tariff negotiations between countries comes into play, too. It was a while ago now, but I remember looking at a round trip flight to Sydney from the U

Trade and tariff negotiations between countries comes into play, too. It was a while ago now, but I remember looking at a round trip flight to Sydney from the US. The same two planes, in different order (round to the US from Sydney) was half the price. I hadn't planned a year in advance, so I couldn't pull the trick mentioned above.