Why are chain stores in the CBD but not the inner city area?

It can be seen that commerce (in particular large department stores/chain stores) is willing to pay the greatest rent to be located in the CBD. The CBD is very valuable for them because it is traditionally the most accessible location for a large population. This large population is essential for department stores, which require a considerable turnover. As a result, they are willing and able to pay a very high land rent value. They maximise the potential of their site by building many stories. As you move from the CBD, commerce is unwilling to pay as much for a site. In fact, what they are willing to pay declines rapidly.