I know I've answered this question before in the last 6 months here but can't seem to find it in the search.

Basically it was a class issue. Most forms of football - Rugby and soccer, and their forerunners (from the working class 'mob football' variations) were played casually until the second half of the 19th century. They were local games, with very little written rules or organisation - the Sedgefield ball game and Haxey Hood are still played today, and have very different rules. Most of them even incorporated local landmarks into the game, so couldn't really be played elsewhere.

By the second half of the 19th century, the railway system in England was good enough and cheap enough to be able to transport your best players to other locations to play other towns, ad naturally many clubs jumped at the chance to do this. As such the games had to be regulated. And to do this they needed men who were educated enough, had enough free time and money and garnered enough respect for their authority to be taken seriously - mostly upper class gentlemen based in the South.

This worked a lot better, although the problem developed that many of the clubs formed by the middle and upper classes could devote a lot more time and money to their players. The working class clubs became fed up of this advantage, and made an agreement with many of their players employers to pay them compensation for 'borrowing' their employees for training. The RFU did not respond well, with many of the middle/upper class clubs enjoying their advantage. So on the 28/8/1895 at the George Hotel in Huddersfield 20 (later 21) clubs from the northern industrial heartlands of Lancashire decided to 'split' from the RFU and found the Northern RFU, which would allow player compensation in a similar model to that used by the Football (Soccer) league formed 7 years previous by 12 Northern/Midlands clubs.

This time was also a period in which Britains Empire was in full swing. British colonies worked in one of two ways (and I'm generalising massively here). The first model was to go in and hold important locations while either subduing or persuading the native population to trade beneficial to Britain, the second was to find underpopulated fertile lands and export colonists there as farmers.

The first model didn't require massive numbers. Upper and middle class as administrators, the only lower class British that would find themselves in Burma, India and Africa were soldiers and sailors on tours of duty. In the second, however, large numbers of working class people were needed.

The US was colonised far before the 1870s explosion of ball games in Britain, but Australias coast line hadn't even been fully mapped till James Cook in 1770. And the high point of immigration to Australia from the UK was the second half of the 19th century , with them the working class immigrants brought their opinions and attitudes towards sports. Thus by 1907 there was a split in the sport in Australia to mirror the way it was played in the UK.

By contrast the upper and upper middle class British were able to travel and live in far more locations and needed far fewer people to gather the funds and knowledge required to form clubs and leagues. The histories of many of the worlds most famous Rugby Union and Soccer clubs begins with a small group of British or French expats, particularly in Argentina.