Alf seems to be missing something about that wonderful element in our economy called free enterprises.
This is the idea that one business can compete with another by offering better quality, or lower prices, and so on.
It requires business people to strive for efficiencies to trim their costs.
Labour costs are part of this.
But the FIRST Union apparently would prefer all supermarkets to pay much the same wages.
Presumably it expects them to charge the same prices, too.