You can employ a lot of janitors for the cost of running a fleet of Roombas. It's the classic case of tech being 90% there. You still would need a janitor to

You can employ a lot of janitors for the cost of running a fleet of Roombas. It's the classic case of tech being 90% there. You still would need a janitor to do the side jobs that the Roombas missed, and to keep an eye on them. Also things they can't do, like wiping down doorhandles etc. Easier just to pay the janitor to mop the floors. You could do away with Janitors if you designed the space specifically for the robot cleaning technology. But that would be designing with the object of robot cleaning in mind, which would mean ensuring no inaccessible corners, wall-hung furniture, charging/storage points. Maybe that will happen in the coming years.