Hams communicate with each other on behalf of other people.

An amateur radio operator license is required for someone to act as control operator for an amateur radio station.  A non-licensed person can act communicate over your radio, but a licensed person must be the control operator.  So you can not just give your radio to event staff for the day.

Amateur radio is different from various other services such as FRS, GMRS, land mobile,... which do not require an operator license to use.