Alan and Lucy have four children, two of whom are adults and two are minors. They have basic wills leaving everything to one another and then to their children equally.
They both die in a car accident, and the superannuation is paid to the children in equal shares. However, the adult children pay a considerably higher rate of tax than the minors (who receive it tax free), so there is a discrepancy between what the children receive, and the ATO receives a sizable part of the estate.
This could have been solved by a simple superannuation proceeds trust in the Will, ensuring the superannuation is paid only to financial dependants, together with a clause equalising benefits between the four children.