> For instance, although Klaeysen holds a PhD, she won’t book a flight with the “doctor” title, because it implies she’s a physician, which may afford her prefe

> For instance, although Klaeysen holds a PhD, she won’t book a flight with the “doctor” title, because it implies she’s a physician, which may afford her preferential treatment. Anyone who thinks that 'doctor' is reserved for physicians deserves whatever his mistake costs him. As for the broader ethical issues: if one party wishes to charge differing rates according to certain attributes, then it's a-okay by me if the other party wishes to signal different attributes. What's sauce for the goose is sauce for the gander.