It is estimated Australians will save hundreds of millions of dollars now that the big four banks over the weekend agreed to ditch fees for customers of other institutions using their ATMs to withdraw cash.

CBA was the first mover, and within hours the other three big banks quickly followed suit.

This is a good move for customers, and one that is long overdue.

Reserve Bank of Australia data shows Australians made more than 250 million ATM withdrawals from banks other than their own last year.

The average withdrawal fee is about $2, but when using a "foreign" ATM at a bar or casino the cost can run as high as $11, and on overseas transactions it can hit as high as $20.

Taking away those annoying and unnecessary fees will no doubt result in more happy customers.

But one is kidding themselves about what this is really about. Their motives are not completely altruistic.

Bank executives didn't wake up overnight worried about fee gouging.

They will keep charging Australians hefty fees for banking with them because, well, that's how they make a big chunk of their money.

Australians now pay $4.41 billion a year in banking fees, which are mostly linked to home loans and credit cards.

According to Reserve Bank data analysed by RateCity, the fees collected from credit cards in the 12 months leading to June 2017 totalled $1.56 billion - an increase of $48 million from 2015.

Home loan fees also hit $1.24 billion, an increase of $5 million from the year before.???

The real reason, as well all know, that CBA axed its fees - and the other banks moved in sync - was to address a bad image problem.

CBA clearly needs better press following the scandal at its life insurance arm CommInsure, and the more recent news of Austrac investigating it because criminal gangs allegedly laundered more than $70 million through the bank.

But the bad news won't evaporate until the big banks completely revamp their corporate culture. That takes time and genuine leadership.

In the meantime, APRA has launched an independent prudential inquiry into governance, culture and accountability at CBA.

And Labor continues to demand a royal commission into the banking sector.

"There hasn't even been a banking royal commission and we are already seeing the pressure of it, by seeing the ATM fees removed," said shadow minister for small business and financial services Katy Gallagher.

"Imagine how we could get better banking for all Australians if we had a banking royal commission."

Just imagine.

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