The podcast did say the UK is one of the earliest starters. So rather than asking "why is Aus so late?", which it is not in comparison to other countries, it is early. The question is "why is the UK so early?"
Yep absolutely!

I started school at 4 and turned 5 around 6 weeks later in March. While I did well academically, I was painfully shy and really struggled socially. My parents say that in hindsight they would have kept me at home another year. I do remember not enjoying the first half of primary school because I was so shy.

My DD missed the cut off to start school this year by 16 days. Glad the decision is out of my hands! I'm happy she'll start next year at 5yrs 8months which I think is perfect.