Suppose I offer you three boxes and ask you to choose one. The first two are transparent, free, and contains an apple and an orange, respectively. The third is opaque, costs a penny, and contains either an apple or an orange, depending on a coin flip I made. Under expected utility maximization, there is no reason for you to choose the third box, regardless of your probability function and utility function. Under UDT1, you can choose the third box, by preferring <apple, orange> to <apple, apple> and <orange, orange> as the outcomes of world programs P1 and P2. In that case, you can't be said to have a belief about whether the real world is P1 or P2.