I live in Australia and whilst I agree that there the tap water is safe to drink I do think it's a bit crazy lumping the whole country into one category.

There are some places in Australia/New Zealand where the tap water isn't drinkable and even areas where it can't even be used to shower (to harsh on skin).

That being said I agree with others that Seoul and Hong Kong both have perfectly fine drinkable water and most of the hotels that I've stayed in across both cities have stated that it's okay to drink the water.