I find the root cause is not so much size... and more so younger sibling syndrome.

Australia/New Zealand have a... very, very, very deep-seated feeling of inadequacy, comparing themselves to large Anglophile nations.

There's a genetic urge to "impress Mother England."

For Australia, also a deep seated desire to prove they're not an island of criminals.

For New Zealand... a deep seated desire not to be left off maps.

It's not so much size... there's just a culture of needing to be a better place to live than America. To stop people moving away.

Edit: root cause. Not benefit.