(Mainland) China has regulations for milk. Including banning of chalk. Alas, those regulations aren't enforced with much teeth in practice, so consumers rely on reputation and brands. Specifically, they buy milks from oversees, like Australia, because of their superior reputation.

A big part of that reputation is that Australian companies won't be protected by the Chinese government when they screw up. So it's harder for them to hide blemishes on their reputation (at least to hide them from Chinese customers).