Out of curiosity, just testing it now. I'm testing a payment of $US100. The exchange rate proposed by HSBC Global View is:
1AUD = USD 0.6457465
on Revolut, it is 0.65733
on IRESS which is my trading platform, it is 0.6591
I see IRESS as the "true" interbank rate;
Revolut as pretty close to...