This is not actually the interface that is used on the Dragon. This is a docking mechanism, which allows autonomous connections between two spacecraft. The Dragon uses the Common Berthing Mechanism (CBM) which requires assistance from a manipulator arm to mate the two spacecraft.

One of the reasons the CBM was chosen for the resupply ships (including Dragon) is that the CBM has a larger inside diameter and so larger pieces of equipment (such as standard equipment racks) can be delivered through it, while the docking connectors cannot pass them.