In Australia this became pervasive across all banks for the last 25 years. It got to the point where, around 5-10 years ago, new national rules were mandated that foreign income could only be assessed at some minor percentage of its evidenced volume under the epithet "loan serviceability criteria". At the face of it, these rules appear to have the public's best interests at heart. But in reality, they simply lock out anyone that isn't a locally registered card-carrying commuter wageslave (eg. cross-border entrepreneurs, immigrants, etc.).
So the new scam - from multiple independent sources - is apparently people from Singapore taking out loans in Chinese Yuan Reminbi denominations for Australian property against Singapore or Hong Kong banks, then coming to the Australian banks and having them "transferred" (internationally, and across currencies!) which allegedly sidesteps the local restrictions. The fact that I know this simply from talking to bank staff as a stranger shows how extremely pervasive these sorts of things are.
WRT your other foreign income/asset comments its much less nefarious. The local banks are focused on AU income and assets because it is directly tied to serviceability and recovery. You can do loans based on foreign income/assets but youll pay a few percentage points for the risk and conversion problems. The international loan outfits are usually smaller, though HSBC is a big one IIRC.