This is a payroll interpretation case. The Court was not deciding whether every employee had been treated fairly in a broad sense. It was construing the words of a particular enterprise agreement and deciding whether allowances were included in the rate used to calculate penalties and overtime.
The Court accepted Hitachi's construction. The relevant base hourly rate was the applicable hourly rate in the schedule, excluding the allowances. The Court declined to give waiting-time declaratory relief because there was no longer a live controversy on that issue.
For employers, the practical lesson is to convert awards and enterprise agreements into payroll rules with examples. A payroll system should not guess whether an allowance flows into overtime, penalties, leave or termination payments. The legal team, payroll team and managers should be using the same interpretation before employees raise a dispute.