According to my dad, soldiers are beer cans. “Throw 'im in the graveyard, another fallen soldier’s done his duty”.
IME, butter on sandwiches in the U.S. does depend on region. Here in West Michigan, where everyone has a Dutch grandma, butter on sandwiches is common (but wrong, in my opinion.) Buttered ham buns are served in many a church hall.
So maybe it’s a European custom that made its way over here. The more likely you are to have an immigrant grandparent who cooks old school, the more likely you are to come across it. In more cosmopolitan cities, where people learn cooking from tv and restaurants and not their grandma, you don’t see it.