Hidden from sight, the below grade portion of a building typically serves some essential function.
Parking, garages, some non-critical storage and laundry area are commonly placed underground. Here the waterproofing requirement is not very strict.
However, for important function rooms, storage and technical areas like offices, high-end moisture-free data storage centres filled with high-tech equipment; any of these services may be located below grade in buildings.
In many countries, it is important to have special rooms in Basement in case of unfortunate circumstances like war, earthquake, etc.