Might have found the answer to my question
“Australia produces the best sprinter-milers in the world,” Orton says. “We’re not so good at breeding stayers, not compared to Europe or New Zealand. In New Zealand their horses tend to grow and develop skeletally a bit slower, for reasons such as the ground being softer.
“In Australia, there’s more sun, the grass is higher in protein, the conditions are more conducive to a fast-growing animal. You can hope for results earlier. And I believe we’ve got to breed to our strengths.”
via https://www.tdnausnz.com.au/edition/2019-10-30/peter-orton-and-the-worlds-best-teacher