That’s way too basic to be a solution. If you take from them they’ll simply take it back from us by cutting jobs and services while raising fees.
We should be making it harder if not outright illegal for them to arbitrarily cut costs in the way they do i.e closing branches, offboarding atms, making workers redundant to keep up profits. They are in many ways a public service and the service component is worth protecting.
Countering this behaviour would be far more impactful to Australians and the economy than just having them hand a bag of money to the government.