It might be a little more revealing if only truckers were allowed to use the interstates. As it stands, it mostly proves that bodies get dumped along the roads that are most used by motorists of all sorts.
Yes. The article is a paean to the FBI. But if you read it closely, they have hardly caught any perps, and those seem to have been caught more or less by accident rather than by using the database.
Moreover, bodies found by the Interstate weren’t necessarily dropped there by truckers, as you say. Wouldn’t mobsters also find it convenient if they wanted to dump bodies in other jurisdictions, for instance? Or car drivers? or hitchhikers?