It doesn’t work like that though.
Swimmers get changed in the changing rooms, they have a call time to be at marshalling or in the call room where officials are stationed to send them out to the blocks.
There is no need for officials or other event staff to be in the changing rooms.
At big events, if you miss your call time or fail to marshal you don’t get to race. At local events, if your swimmer is missing from marshalling you send another swimmer of the same sex to find them.