As a former fast food manager, I would imagine the manager would like to know this is happening. We didn't allow that to happen and the employees were trained to stay 2 tables away while cleaning up after a lunch or dinner rush. Sometimes you would have a family come in with untrained kids that thought the floor was their playground. When that happened we would ask if it was ok to clean the area if it was next to an occupied table, but under no circumstances would we sweep or mop under an occupied table.