It should be noted that the list at the bottom of the page is in alphabetical order. Were it to be in order of precedence, the UK - principally England - would be at the top as it is the centre of the world and the Universe as we know it, Jim.
For the Aussies, I think that must be because there isn't a .au site as such but they are very welcome as they use a similar brand of English as do we and the Americans. We have hundreds of posts a day from folks with Indian sounding names who's English is a darned sight better than my Hindi!
I think that most of the India(n) named users are actually from Canada and India, and UK. I'm in Australia, my brother likes to read the articles in TH but not participate even though he is quite adept with computers. UK is English, Australians do speak a type of "English" and English is the predominant language in India particularly with students (or of that age) to whom would be the ones viewing posts more than actually participating, either asking or answering.
I actually had (have) an account with the US site but it was not a good format and there was a distinct echo around it so I kept this account where all the action is happening (most times)...
Tom's Hardware US is pretty much the melting pot of the Tom's sites, with users from all English-speaking countries, including India, Australia, New Zealand, Canada, etc. Chances are, if a series of posh imperialists planted a flag in your country on behalf of a frumpy queen - we're there! Countries for Tom's tend to be segregated by language, rather than specific to region.
It's good but to my surprise, the Aussies played it straight in spite of the temptation to do otherwise.
If you ever get a chance to see Opera Queensland's version of Pirates of Penzance, grab it quick - it's hilarious from start to finish with lots of digs at the Mother Country. Without a doubt, it's the best DVD I ever bought, having watched it on Sky Arts one afternoon.
My other thread about how to become a moderator got really thread-jacked that one other Moderator had to Close it.
The Community Manager in this case is one of the culprits! I'll have to report his actions and possibly his account may get a notice of suspension, wouldn't that be hilarious!
Well, at least I did get a decent reply to the Question, perhaps just a warning notice about off-threading, might be in order.