The beds of pickup trucks are largely vestigial, they’re designed as crew plus trailer haulers. A truck like that will be advertised pulling a yacht on a trailer over the Rockies. It’s got enough bed to put a gooseneck hitch in. A van or SUV will keep up with a pickup with a Class IV hitch, but a pickup truck is a miniature tractor trailer now.

Using the bed as a bulk cargo box is actually pretty rare these days.