The car/truck split is done with the european view of that (as the site was first made by French & Belgian members).
So you have to see "trucks" as "heavy trucks".
Here what we call a truck is something more than 3.5 ton, that requires a special driving license.
So in chassis-cab you find light tow trucks, small cube trucks (a cube posed on a chassis+cab), etc.
This was made because for us (F & B) these vehicles are in the same category than the cars, in weight, size and license requirement.
For the tax services, they are considered as "utility", but a hatchback without rear seats is considered the same.
I know that in USA the SUVs, pickups, etc. are considered as truck like is the semi-trailer tractor truck...
Heavy chassis-cab should be listed as "simply trucks". In French it is called "porteur" but I still have not found its real English equivalent.