You know that this is mostly rubbish? The temperature of a fire isn’t dependent on the ignition source. It is multifactorial, based on the type of fuel, how much there is, supply of oxygen – i.e. wind – and how hot the environment is to begin with. Any blacksmith pumping his bellows over a charcoal fire will explain that wood doesn’t give enough heat.
The sort of low level fire described doesn’t burn the tree crowns, which is what makes hot dry fires – such as the ones we’ve had this summer – so dangerous and destructive. On a hot windy day the eucalyptus leaves and oils fuel a hot fire that races from tree to tree at lightning speed, making an updraft that pulls in more oxygen and sends embers speeding ahead to create spot fires. This sort of fire is almost impossible to fight and the fires you describe as cultural burning do nothing to prevent them.
And why do you think a hunter-gatherer society might have set fires in the first place? To pursue some cultural objective of making a green and pleasant land, or to destroy habitat for animals, flush them into the open, and kill the slow-moving ones? They had no agriculture; their food source was the plants and animals in the bush.
Controlled burning reduces fuel load and makes fires less common. That’s why we do it. Don’t kid yourself that the costumes or the customs or the culture of those doing hazard reduction burns makes any difference to the physics of fire.