that's pretty demeaning. there's certainly overlap, however that's mostly US TV and movies being exported, which also happens in other (non-English speaking) countries. but each has a distinctive culture, with different TV shows, music, artists, celebrities, politicians, words, lifestyles etc.
now, speaking english with ease does make it easier to pick up on the differences. but it still takes effort to engage with people. i've seen people from other countries integrate easily because they were either very socially aware or simply made the effort, regardless if they spoke the local language with ease. this happens in countries and with people that aren't the UK, US, or Australia or from there.
Calling the US, UK and Australia "identical cultures" is pretty bad, just because they all speak English? True, they share common history, but they also have so many other influences that they're quite different. E.g. Wales, a country in the UK, even has it's own language which is still taught in schools and used officially everywhere.
now, speaking english with ease does make it easier to pick up on the differences. but it still takes effort to engage with people. i've seen people from other countries integrate easily because they were either very socially aware or simply made the effort, regardless if they spoke the local language with ease. this happens in countries and with people that aren't the UK, US, or Australia or from there.