In the old days when travel agents booked flights, most would register the name under "Dr.", and it could be picked out of a flight manifest, or whatever they call the passenger list. The flight attendant could them go to them and ask whether they could help. I suppose it could work the same buying tix on this thing they call the "Internet"....
Aside from the fact that your local dog catcher could buy a ticket entitled "Dr. Joe Schmoe".