I work in the travel industry as a programmer (god only knows for how much longer) - I can tell you that Sabre and other GDS's are only used if you go through a travel agent or use some online reservation systems. If you book through the airline's systems or on online reservation systems they likely use the airline's systems to track travel instead of GDS since the GDS wants to take a big cut of every ticket sale. And obviously only legacy travel companies like Hertz and Mariott integrate with GDS's, new travel companies Uber and Airbnb likely don't have any relationship with Sabre.
You're only likely to be in a Sabre system if you've been booked by your company through a travel agent and rent using legacy car/hotel companies also through your company's travel agent.
You're only likely to be in a Sabre system if you've been booked by your company through a travel agent and rent using legacy car/hotel companies also through your company's travel agent.