In the city here, I always see those trucks modified to vacuum debris from parking lots. They begin their "cleaning" thing around 12AM. They seem to just shoot

In the city here, I always see those trucks modified to vacuum debris from parking lots. They begin their "cleaning" thing around 12AM. They seem to just shoot the stuff right up into the air and make a huge mess. Not sure if they are supposed to work that way, or the machinery isn't being maintained, etc.