Arguably English became the default by a very large historical chance: that Napoleon sold off his North American colonies - a huge swathe of what is now the United States - to finance his wars in Europe. At the same time that both France and England were sniffing around Australia, France again was distracted by its wars.

Both the United States and Australia could very easily have been French speaking, and if they had been, I suggest we'd be having this discussion sur internet en français