Of course US usage far exceeds Australian and always will as per the link you supplied:
The spectrum crunch is not an inherently American problem, but its effects are magnified here, since the United States has an enormous population of connected users. This country serves more than twice as many customers per megahertz of spectrum as the next nearest spectrum-constrained nations, Japan and Mexico.
And also there is alot of unused spectrum:
There are also businesses such as Dish Network (DISH, Fortune 500) that have large spectrum allotments but aren't currently using them. (Dish is exploring its options for either using or selling its spectrum. A group of cable companies with unused spectrum recently struck a $3.6 billion pact to sell their holdings to Verizon in a deal that's facing heavy regulatory scrutiny.)
But I agree wireless is not a 'whole' solution however it would be a perfectly viable solution for country regions backboned by fibre instead of this ridiculously stuid and expensive need to connect every household to the fibre.
