People congregate around water sources. They don't just gather anywhere and make it happen. Ports are where they are due to the location having the necessary re

People congregate around water sources. They don't just gather anywhere and make it happen. Ports are where they are due to the location having the necessary resources to support a population servicing a useful(1) industry. Similarly, moon or Mars bases will be where they are if the location has some useful(1) industry and sufficient resources to support a population servicing that industry. (1) 'Useful' to them, and not necessarily to everyone everywhere all the time.