There’s also a strategy to jump the line. Say there’s a talk that just took place on the top floor roof deck of a small ~20 floor building. People who don’t want to wait in line with a hundred people, can take the stairs down one level, call the elevator on the way up to enter the car before it is filled, ride it up one level*, and then ride it all the way down to the ground floor.

To prevent a riot, the building should probably deploy an employee with a fire key to manually operate the elevator.

* Elevators will answer an up button call while it is going to meet a down call from the top floor, but they will answer that call before filling any new down instructions, so you do have to ride to the top first.