The black friday fires started in January 1939. Australia at the time had seriously inadequate training and equipment to deal with this. It also started during a heat wave. In total around 2 million hectares were burnt. In 1851 we had black Thursday in which 5 million hectares were burnt. That fire started in February.
The current fires have now burnt close to 6 million hectares and the fire season started in September. The areas currently being burnt include temperate rainforest that hasn't burnt in living memory. There are concerns from climate and fire experts that some of the areas have been damaged so badly that they will not be able to recover.
Also, these fires are far from over, and many new fires have started in the last couple of days.
In the last few weeks Australia has recorded the hottest temperatures on record, while being in one of the worst droughts on record, and this hasn't been a single year aberration. The last 10 years have each set new records for the highest temperatures on average.
The only reason that casualties have been so low is that we have good communications with areas under threat, and residents in these areas know to leave when the threat gets beyond a certain level.