A great paradox

If Australia's banks are doing so well with so much cash on hand why is the Federal government introducing a backstop liquidity regime? 

On the one hand there is giant CBA of the big four announcing big profits and dividends:

COMMONWEALTH Bank is expected to post a record $7.6 billion full-year cash profit and potentially reward shareholders with a special dividend as the reporting season kicks into gear this week. 

With the chase for yield pushing the banks' share prices to record highs, CBA's capital management will be closely watched ahead of quarterly trading updates from rivals ANZ on Friday and National Australia Bank next week. ANZ, like NAB and Westpac, has a September 30 year-end date.(here)

But the international media smells a sector which is overvalued, overexposed and lacking growth potential:

Higher payouts signal confidence, but they also imply managers have no better use for the cash. That leaves the big four trading at a whopping two times book value. CBA, by far the largest and now seventh-biggest in the world by market capitalisation at $107bn, is trading on 2.7 times book, which can only be considered extreme for a bank with four-fifths of its loan book in its home market, where economic growth is slowing and government finances are worsening.
Australia’s banks have for five years been a great bet, with price gains of two-fifths compared with a tenth for US banks and a one-third loss in Europe. But the best is past. Returns on equity over that time have slipped by a sixth while those lumpy loan books – which have not been tempered by a housing market downturn, cannot deliver the profits growth implied by their rating. The return of capital implies the banks themselves cannot see value in seeking growth, either.(here)

While Australian regulators seem to be preparing for a liquidity crunch while analysts point to a possible trigger for recession from China.  Anyone with some alternatives?