There are 25,000 passenger planes for moving people and cargo. There are another 14000 military jets. Passenger travel around the world will triple the demand for vehicles by the 2040s. If Starship can become one thousand times safer then it could replace passenger jets for moving people and cargo for longer distances than 2000 miles. Half of the passenger jets could be replaced. This would be about 35,000 Starships.
Hundreds of Starships could be sent to Mars every two years to colonize and create a city. If a million people were moved over three decades to Mars. Each might take 100 people, this could mean ten thousand Starships if they are used mainly for one way travel and then as habitats or moving around Mars.