More specifically, this talk sheds a lot of light on it. The opening statement alone is interesting: that despite the conventional wisdom it is actually better to be born into a large cohort than a small one. Because being in a large cohort brings collective voting/political power and buying power.
One thing to note about this breakdown is that it wasn't legislated with good intention but it was implemented in a very malicious compliance way that completely counteracted the original intention.
This receipt was legislated by the conservative party in Australia under Tony Abbott, the surface level intention was to "show where people's tax dollars are spent". However the underlying intention was to show welfare spending as a huge category that totally eclipsed all other spending in order to demonize welfare, particularly unemployment welfare. In order to build public support for rolling back that spending.
However when the letter was implemented, the welfare category was further broken down as you see here, completely working against the narrative that the government at the time was trying to spin (that unemployment welfare particularly was a huge drain on society).
The Androids book by Chet Haase provides a good look at the early history and design decisions of the platform and how they came to be made.
At the time there was a debate inside the team over what language their app development framework should use, with native C++ and Java being the two main options (I think there might have been another option or two, I can't recall). In the end Java won out, and from memory one of the main reasons was to make it easier to make apps and not need to think about the lower level parts of the platform, i.e. the platform takes on the complexity internally in order to lower the barrier to entry for app developers. The idea being that a lower barrier to entry would result in more apps being developed for the platform. For a brand new platform that lives and dies by the apps available for it, that's a pretty sensible trade-off.
And yes, Android has a lot of vestigial remnants of the past, the Android framework team has been very particular about maintaining as much backwards compatibility as possible within the framework.