I can only comment on the Queensland situation, but I imagine it is similar, if not most the same. A deceased person cannot own property or deal with property, for obvious reasons. They cannot execute a contract or a transfer of land. The executors/personal representatives of the estate are the ones who hold the estate assets on trust until they are delivered to the beneficiaries - unless it is joint property, which automatically goes to the survivor(s).
In order to have the property registered in the name of the executors, a transfer must be lodged with supporting evidence that it is a valid transfer (usually a certificate of death and an original will/copy of probate). In Queensland this is called a ‘transmission by death’.
There’s no stamp duty on this transfer, as it’s a required step in the administration of the estate which the government recognises should not be dutiable.
The estate can only deal with the land once it has been transferred in this manner.