All it is is international economics and the exchange rates. The Aussie dollar is - and pretty much always has been - chicken feed in comparison to the pound.
The world is becoming more global, and more and more people from western countries travel to other nations for parts of their careers - including footballers now it seems.
There actually is no answer, so why whinge about it, or try and find some answer of how to keep our players. If they are greedy for the maximum dollar - and for a bit of different life experience - they will pursue deals in Super League. There is no loyalty to clubs or contracts anymore in either direction, and this is what we reap as a professional game.
As for England not competing internationally, these things tend to come in waves. I remember the Windies being the cricket team to beat in the 70s and 80s and now they are a bunch of no hopers. I remember India being pretty poor in the 70s and 80s and now they pretty much own our arses...
We are dominant, but in the 50s and 60s we were behind England in rugby league - and even France for a brief time? Things change, and change back again.