The whole bloody lot are incestuous fraud artists
The on-line res systems, GDS - Global Distribution Systems, evolved from airline based res systems into multi-carrier or universal systems.
Simply put, a travel agent, or vendor. inputs an inquiry and the res system kicks out a choice of slights. Due to their affiliations these flight presentations were skewed in favour of the airline owner - in the case of Sabre, now independent Sabre Holdings, it was American Airlines - then the U.S. government stepped in because of this bias and flights were listed by time of departure.
This why air carriers always list their morning departures at impossible times, even before the airport allows flights to begin, to get early positions in the screen listings.
The res systems made their money when a seat was "sold", the air carriers account was debited with a handling charge and the travel agents account was credited with a small piece of the action whilst the res system grabbed the most.
If a seat sale was cancelled the process was reversed - which all seemed fine. The res systems were, in fact, doing the accounting for all three parties in the deal.
Airlines can't, under IATA rules, mess with discounts, etc. To get around this restriction air carriers introduced 'contracts' where they provided seats at a discount to a travel vendor based on 'production' or ethnic origin. (This why it is often best to buy overseas flights from a travel agent ethnically affiliated with your destination)
On occasion the res systems had technical problems where their accounting systems screwed up and either the carriers or the travel agents lost out, monetarily.
SURPRISE, no one bitched, no one noticed they were getting gyped by the res systems. These 'incidents' continued for years with everyone, except the GDS, losing a small percentage.
Then some airline accountant got smart. Instead of accepting the GDS accounting as gospel, he decided to audit their returns with actual seats sold. Big problems for the GDS, but another opportunity for IT - automatic seat sales/GDS reconciliation.
Remember ALL THESE TRANSACTIONS were ORIGINATED by the independent TRAVEL AGENT. In order to actually sell a ticket and accept money on behalf of airlines, travel vendors have to be IATA approved. Individual airlines made travel vendors 'authorised' by issuing a 'plate' which would be inserted in the manual ticket machine so the right codes, and discounts, were applied.. This 'plate' data was later held by the GDS so they automatically printed the data on tickets.
Many of the discrepancies were sorted out between the GDS and the airlines but many airlines didn't have the clout to deal with the GDS so they came up with a new idea -screw the weakest link. These 'charge backs', aka Debit Notes, are made for everything: agent booking errors (including GDS errors), credit card refusals, etc.
Then some travel agents decided to check out their GDS accounts and they found that their sale 'credits' were 'short'.
This has happened with Sabre and, at least, Galileo - I know as I was sued by both (and they both lost) for warning travel agents through a web site, that I am one moderator of, of these losses.
To demonstrate exactly how amoral GDS are consider: they are travel agent suppliers, they collect all passenger identification and contact info, they know all about travel agent customers, as well as travel agents.
In normal businesses suppliers don't sell against their customers. But travel is not a 'normal' business. Sabre set up Travelocity so it can retail against travel agents (Travelocity has to use real travel agents in some locations to issue tickets because of law). In other words Sabre gets the transaction handling charge and the discount through the 'contracts' it holds through Travelocity.
So today we have all these incestuous crooks complaining because an honest broker, Google, wants in and that all their little deals, that rip off passengers, will be exposed.
Tough luck, I say, the retail travelling public deserves transparency and these 'friends' in the travel trade should face true competition!
P.S. To get the best, and safest, deals:
1. Pick a reliable travel agent who will appreciate you and your business;
2. Only buy from IATA approved travel agents;
3. Make sure your travel agent can be contacted out of hours by e-mail for emergencies;
4. Make sure your travel agent is bonded - often through a trade organisation;
5. Note that buying travel from the company organising the travel/package means NO insurance!
6. Not one of the members of FairSearch.org will provide all of these passenger friendly benefits. Most are not insured to protect their customers, either.