I can't understand why that is the case. Other less developed countries or less affluent ones are miles ahead of Australia when it comes to COVID vaccinations.
Its very simple, really.
Since this pandemic began some 17 months ago in February 2020, Australia has experienced relatively minimal societal impact (less than 930 total deaths) due to the effectiveness of closing of national borders. This has meant a comparatively lesser degree of immediate need for vaccine in this country. Hence, it is easy to understand that we (as a nation) were more concerned about other countries need where there was far more immediate / desperate demand.
It also didn't help that our Government strategy rested on only two approved vaccines, one of which is being manufactured locally and is still considered controversial whilst not approved for use in the USA, despite it's European / British origin. The other being Pfizer.
You suggested that Aussies should "pick up the pace". I am sure we would, if we could get more shipments of Pfizer as well as promised Moderna and Novavax - the latter two where initial shipments are expected during Q3 or Q4. Luckily, Pfizer's management has recognised the issue and is already accelerating deliveries to Australia.
Oh, and BTW - a number of upthread comments have referred to "lack of demand" across the USA-Australia route. There is NO lack of demand. What there is is a complete lack of Australian Government approval to allow foreign nationals into Australia or Australian citizens out. Believe me, there is plent
y of demand within Australia for travel anywhere - and I am perfectly sure that the same reciprocal situation exists outside Australia.
What we are wary of is .. importing further cases of active COVID by allowing unfettered travel into the country until a reasonable degree of vaccination coverage has been achieved. Many may disagree with this policy - but it has served Australia well, so far ~ but at an admittedly high economic cost.