They probably got bumped down the list, for now. If my weight limit was met with half a truck of lead, but got paid more for a lighter weight full truck of rolled paper, who do you think I would charge more?
A short primer on how truck freight charges work is in order here.
All trucks are restricted to a certain weight. Most Dry Van freight (the plain old trailers you see on the road are Dry Vans.) you see, the company wants as much on that trailer as possible. It costs the same to take a trailer from point A to B if it's full of half full.
Most of those trailers you see are not full.
Trucking companies classify freight in density ranges. The higher density, the cheaper per pound it ships. This is for LTL, or Less than Truck Load. A full trailer is different.
For instance, a barrel of lead would go Class 100, which is he least expensive class per pound. It's very dense, takes up a relatively small amount of room.
A pallet of toilet rolls is not very dense at all. It goes class 250, a very expensive per pound class.
So, it costs more to ship bulky, lightweight freight, but does the freight company make more ? Not really, as the companies charge per class/pound. The bulky freight just takes up more room.