The Simpson Desert is not located in any city. It is a desert in central Australia, so is therefore far larger than any city. Neither are there cities within the Simpson Desert, although there are townships and settlements located sporadically along its borders.
Millions of people around the world live in the desert - perhaps 99.999% of them in cities and towns. They have any food they could wish available to them at the neighborhood market or restaurants. Food is not a problem in the desert.