When a Cigarette ends

Escorting my daughter to train to Helsinki, seems that she is fit enough to go to work (after the hard flu).

As she had gone on, the three men and one woman did end their cigarettes and dropped the ends onto the ground. And went after her into the train. Door closed.

I wonder why smokers have to throw the ends like that. Even when there is a place for cigarette ends.

Susanna