Unless you can tell me right now that you've studied the systems in detail, either as a university course, or you've seen some study done on the structures and processes of each of the education systems, I'll just assume you're talking out of your ass, because really, I don't see how you could be qualified to make a comment like that, especially in a such a definitive manner.
I have selected the analogy from experience - i can speak from personal experience relating to the ICSE, CBSE, A-Levels and American education system and i've interacted a fair bit with Aussie students up here.
So far, i've found the Aussie and American students to be significantly less rounded than Canadian students, the O and A level students to be a bit better rounded and ICSE/CBSE just sitting on a whole new plane.
Just to give you an idea, i did ICSE grade 9 and i had to do Physics, Chemistry, Biology, Mathematics, English language, English literature, Hindi Language, hindi literature, history, geography, Bengali as third language, a course in morals, woodworking and PE.
Just to give you an idea on English literature, i had to read Tale of two cities, McBeth(original text, not re-touched) and 25 select poems from the last 350 years of English poetry. Yes, this is grade 9 i am talking about following a standard model ICSE syllabus. Ie, enough time to go to school, do homework, eat and sleep on weekdays and finishing your last homework on the bus on the way to school.
As i said, its way way above any other system i've encountered or heard of, barring perhaps the Russian system where they do crazy math at high school levels.
PS: I have treated this whole discussion as hypothetical and therefore, not factual in the first place. What i have proclaimed as facts are independent from the whole 'Tendulkar if he was an Aussie' scenario - the facts i've claimed are :
1. Tendulkar's performance before his 20th birthday was stunning : Think on this- he didnt just come out in an era of no-hoper bowlers and super-flat pitches like today where almost every team has atleast one or two 50+ averaging batsmen. Infact, only three others were averaging 50+ and those three happened to be Miandad, Viv and Border nearing the end of their careers. Ie, for a 20 year old to average 50+ in that situation is a big deal and in my personal opinion, significantly more stunning than Ponting averaging 60+ or Yousuf scoring 1800 runs in a calendar year.
2. Tendulkar's performance in his early/pre-teen years is superior to almost any other player - this too, is a fact once you realise that he was sporting Bradmansque figures while competing with kids 3-4 years his senior. This may not be a big deal in international cricket but for a 12 year old to school a 15 year old is a big deal, given that a 15 year old is significantly more developed physically than a 12 year old
3. Tendulkar earned his test spot. Insinuations and suggestions have been made that he got a break because he played for a 'weak' team and if he were in a stronger country cricketing-wise, he'd be held back. Well, Tendulkar earnt his test spot by averaging 50+ in FC cricket as a 15 year old. That kind of record from such a young age would make a case even in today's Aussie lineup.
Based on all this, i've said that there is no cricketing argument to claim that Tendulkar wouldnt have debuted till he was 20-21 in Test cricket.
If a guy is good enough to average 50+ as a 20 year old in Test cricket in a day and age where only three alltime great batsmen were doing so, he'd have cracked it in Test cricket noticably before his 20th birthday. That is all that i've claimed.