You do not know how much work parking lot sweeping machines do. When you walk down the streets, are they clean? If they are it is all because of those big brushes that scrub those avenues squeaky clean.
You will not see them very often during the day. Usually, they work at night so they will not block the traffic. Their mission is to pick up small garbage and dirt as they can pose danger to drivers. The fact that they collect waste off the road makes the job of city sanitation workers easier. They clean up the sidewalks, while these big machines sweep the rest.
When winter passes and the snow melts, the roads and parking lots can become really dirty, thus messing up cars and passersby. If we would not have these, we would be going more often to the car wash and pay more on detergent. For some this might not seem like a big deal. Now let us imagine a city where the only ones that could clean up the streets are city workers. It would take days to do the job that the parking lot sweeping machines do, and after finishing they would have to start all over again.
If you are looking to clean up your business parking lot areas and make a good impression on clients, look into parking lot maintenance support from CAM.