Comment by EnigmaFlare 5 hours ago
One way I've heard is they don't book your ticket immediately but predict when the airline's price will go down and book in then. I imagine they have far better data to enable price prediction than the general public, and can spread the cost of getting it wrong over their other customers.
From what I remember from working in the industry many years ago, the process is actually split into (at least) 3 parts.
1. Reservation
2. Booking
3. Ticketing
Each step has its own expiration dates set by the airline, which can range from "instant" to several days/weeks. They may also set different cancelation fees for each step. A smart travel agent could in theory use this to cancel an old booking and book again if the price is reduced, but I think some airlines have changed their practice to avoid this.
Keep in mind that I mostly worked for the European market. I know US airlines operate a bit differently from the rest of the world. They usually have more flexible rules around flights and exchanging of tickets.
At least the ones I’ve used have always sent me a ticket number within at most a few hours, and usually instantly. I’d be surprised if that really was a factor these days.