Multimode optical fiber is generally used for campus or building applications due to the ability to use cost effective:

Fiber connectors such as LC and SC are common to both multimode and single-mode fiber and carry no meaningful cost difference between the two types.

Multimode cable is not notably cheaper than single-mode cable; cable material costs are comparable and are not the distinguishing economic factor.

Installation methods for multimode and single-mode fiber splicing, termination, and pathway work are essentially identical and provide no cost advantage to multimode.

Multimode fiber has a larger core diameter (50 or 62.5 microns) that accepts light from low-cost LED and VCSEL-based optical transceivers, whereas single-mode fiber's 9-micron core demands expensive precision laser transceivers at every port. Since campus and building runs are short enough for multimode's bandwidth limitations to be non-issue, organizations gain significant per-port savings on transceivers. This transceiver cost differential is the primary economic driver for selecting multimode over single-mode in intra-building and campus backbone applications.

Network designs using multimode versus single-mode do not differ in cost or complexity at the architectural design level.