The RBA can't control rates, because the banks don't borrow much from them. Bank borrowings are from Australians and overseas. The banks have to pay what their lenders require. If the RBA raise rates it is only because the banks are telling them "rates are rising - if you wish to maintain your semblance of control, you'd better raise by (one quarter; one half; three quarters a percent: delete those which don't apply this time) on the xxth of May, or look stupid".
