Brats and Caminoes could make sense when having bucket seats in the truckbed was allowed (though obviously dangerous). But nowadays I guess it only makes sense for hauling white goods home from the home center and such.
A protectionist law that favored small trucks built in America. Australia has a long history of loving "utes", the car/truck hybrid: https://www.core77.com/posts/88821/The-Australian-Designer-W...
Reading the wiki page it mentions Ronald Reagan owned one and used it on his ranch, which speaks to their versatility.