If British wizards regarded American wizards as nouveau riche, they thought even less of Australia Wizard.
In the eyes of most traditional British wizarding families, Australia Wizard was a bunch of people unfit for polite society.
This was evident from the fact that, after it was confirmed that six schools would compete at Hogwarts, including the Australian school, quite a few students had received letters from home telling them they could lose to anyone but the Australian school.
By contrast, Harry, Hermione, Ron, and Neville had no such thoughts.
Harry's knowledge of the wizard world was still limited to the History of Magic he studied at school. Naturally, his textbooks could not contain anything as outrageous as articles mocking Australia Wizard.
After all, some things, even if you did them, could not be admitted to others. That was especially true of discrimination.
Sirius Black, currently one of his nominal guardians, very likely held such views, but he happened to be away on a long trip and had yet to return, so he could not influence Harry.
As for Hermione, that went without saying. What she disliked most was discrimination in any form. The fact that she was still helping house-elves fight for their rights offered a glimpse of that.
There might have been a little of it in Ron's family, but it was not obvious, and at least it had not affected him.
Neville's situation was much like Ron's. By rights, the Longbottom family certainly would have been prejudiced against Australia Wizard, but the only elder above him was a grandmother who paid little attention to current affairs, so Neville had not been affected much.
But although those four had no such prejudices, most of the other young wizards present did.
Young wizards from Muggle families were a minority, after