Yes, really the optimal plan is to use an Amex that has higher rewards due to its higher merchant fees. Yes, the fees get passed on to the customers, but they

Yes, really the optimal plan is to use an Amex that has higher rewards due to its higher merchant fees. Yes, the fees get passed on to the customers, but they get passed on to ALL the customers, so the people using Visa or MasterCard or cash are subsidizing my Amex fees. Not particularly nice, but optimal!