No, there are a number of airlines systems referred to as GDSs or CRSs (Global Distribution System/Computer Reservation System). Way back when, they were all owned by a particular airline (most of which have since split them off). Airlines all submit their fares/schedules to these systems so tickets can be sold thru various sources, including travel agents/tour operators/consolidators. Each system has access to the same information, they were just developed by different airlines (kind of like a PC and a Mac, they go the same place by different means). One of WorldSpan's strong points is it's international pricing, so it's not surprising that an international consolidator would choose that system to ticket on. American does have a system, Sabre, and it is one of the largest GDSs.

Make sense?