Some of my friends get this argument all the time from their less mathematical business-manager bosses. "Sure, probability applies to playing cards, they're random, but it doesn't apply to business_process_X, because there things happen for reasons!" (I've even heard "sure, probability applies to baseball players, but it doesn't apply to website visitors"!)

Pretty much everything that we use probability to model has underlying causes and reasons, if we could only detect and measure them (at least until you get down to quantum mechanics), but probability can still be a useful way to model problems where either we don't fully understand the underlying causes, or the underlying causes are just too complicated and tangled to directly model.