Taxes haven't remotely been paid in a lot of cases. A while back my brother was renting in Randwick. Neighbours who were his landlord (owned both sides of the duplex) were on the old age/carers pension. Wife was looking after her mum who also owned a place in Randwick. Between them they were probably sitting on $4-5 Mill of property even 10 years ago which would have been bought 50+ years ago for peanuts. They worked in basic jobs so would never have paid much tax in their lifetime.
Their kids were set to inherit the lot tax free. Given the support offered by the government in terms of old age pensions/carers pensions collectively I don't see it would have been that unfair for an inheritance tax to take place. A lot of old money has been made simply by sitting on assets like property in prime locations with little money in comparison generated in taxes by the same families.
