It’s more than that. The biggest issue is you need to use a truck from the warehouse to the train, then wait for a crane operator to lift the container off the truck (this can be hours), then the same thing happens at the other end.

The truck driver isn’t the only one waiting, often trains have to wait too - for example a lot of our tracks are bi-directional so if a train is coming the other way, you need to park your train off the main track and wait.

The extra time isn’t just a logistical challenge (tends to mean you need more storage in supermarkets). You also have to pay the truck driver to sit in a parked truck or train. Trucks are just cheaper.

Finally - a full sized truck can carry far more cargo than the shipping containers used for inter-modal transport. Especially in Australia where we allow really big trucks.

The calculation is different in Europe where trucks are smaller and they also travel slower (80kmh) on busy highways.