The study is here, and says in part,
There are four components that drive fire activity: weather that influences fire spread, ignition sources, biomass accumulation (fuel loads), and dryness of fuel loads (fuel availability)2,7.
Fire ignition factors in Australia include multiple anthropogenic and natural sources. The primary natural cause is lightning, particularly that known as “dry lightning”,
Fuel loads and trends, as effected by climate, human activity and time since the last disturbance, also play a role in determining fire risk25,26. This link is a central motivation for using prescribed burning to reduce fuel availability27, which in Australia is managed through changes in the frequency of prescribed burns28
However, while human prescribed burns in forest management is cited, nowhere did I see the effect of a growing population as a significant cause, both in accidental fires as well as vandalism, as well as in increased reporting. Just how many fire were caused by humans and went unreported in the past going back 90 years versus the modern era? But being peer reviewed by "experts" (which I think is an increasingly abused catch-all phrase) are we to question such?
It is a huge, illogical jump.