Around here that's illegal--you're required to cover loose loads to keep that from happening. I've called 311 once on a truck shedding chunks of old carpet.But yeah, I think a lot of the trash we see out there on the roads comes off garbage trucks, debris trailers and is not intentionally thrown out. I also see trucks carrying an open load of tomatoes and inevitably a few pop out when the truck hits a pothole. There was a sharp turn on a rural highway near my college that always had a pile of rotted tomatoes on the side, where drivers took the turn too fast or piled up the tomatoes too high in back.