I argue using simple models that all successful practical uses of probabilities originate in quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus I claim there is no physically verified fully classical theory of probability. I comment on the general implications of this view, and specifically question the application of classical probability theory to cosmology in cases where key questions are known to have no quantum answer. Overall, this approach offers a certain disciplined perspective on probabilities in physical theories which may yield progress on measure problems traditionally associated with eternal inflation.