UnBorn:probability in Bohmian mechanics

Why are quantum probabilities encoded in measures corresponding to wave functions, rather than by a more general class of measures? Call this question WHY BORN? I argue that orthodox quantum mechanics has a compelling answer to WHY BORN? but Bohmian mechanics might not. I trace Bohmian difficulties with WHY BORN? to its antistructuralism, its denial of physical significance to the algebraic structure of quantum observables, and I propose other cases where Bohmian antistructuralism might have an explanatory cost.