The question "What is the population of Kmart Australia?" reflects a common misunderstanding: Kmart Australia is a retail department store chain, not a city, town, or geographic area with residents. Therefore, it has no population.
If you're looking for demographic data, you might mean the population of a suburb where a Kmart is located (e.g., "population of Burwood, VIC") or the customer base (millions of shoppers annually). But Kmart itself? Zero residents—just shoppers and staff.