What was the lasting impact from the great depression, for both worldwide and australia?

Question

For instance, I have this,

Labour unions and welfare state expanded

Social Security Act -

Unemployment compensation

Old age and survivor’s insurance

Increased union membership

Macroeconomic policies

The only problem is that it is mainly applying to the US.

Answer 1

There are three lasting impacts of the Great Depression.  First, economists became aware of the circumstances in which markets fail and that in the case of market failure, only governmental solutions can succeed.  Since this is the exception instead of the rule, economists are still wary of governmental structures, but it provides a role for strong government in time of economic crisis.  The second was an awareness of the danger of weak states.  Hitler arose from the ashes of the Great Depression along with Roosevelt.  The Papin and Hoover governments collapsed because they did not provide a solution.  

Roosevelt went into office, saying to an aide, if it doesn't work, that he would be the last President of the United States.  Indeed, there was a little talked about coup d'etat attempt during Roosevelt's term.  To prevent wholesale societal panic, rather than arrest the generals, they offered them resignation.  I do not think any major government since has been passive in trying to bring economic stability since.  Prior to that, government did not really see itself as an economic actor.

Finally, for the first time in world history, a theory of money developed.  Gold and silver were the basis of money for most of human history.  The Depression was largely caused by the Gold Standard.  Banking, insurance and brokerage are the consequence of market failure.  In the absence of market failure, banking, insurance and brokerage could not exist.  Financial institutions create markets for risks that could not function properly in a traded market.  They are institutionalized responses to persistent failure in risk markets.  The banking failures of the 1930's as well as the successes in Canada or the United Kingdom acted as natural experiments where economists could observe different regimes, both monetary and regulatory.  

Labor unions were a side beneficiary of the Depression.  Had unions backed Hoover, they would be in the same place they  were before the Depression.  If you note your list, they are all risk transfer functions.  Government took the role of bearing all risks that markets would not and which private insurers either could not or would not.

Government became aware that it could play a valuable role in risk transference.  Unfortunately many of those functions are still with us and currently unnecessary.  Government functions best when it is small, in equilibrium, and large in failure.