Think TV

Why is it that planes flying from South America (Santiago, Chile, for example) to Australia (Sydney, for example) take such a long route (15,000 miles) and refuel in North America or Canada?  Also, South America to South Africa (Capetown) and also South Africa to cities in Australia?  Thousands of miles out of one's way ... St-rrr-aange!

Qantas 747s Fly By Antarctica: