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.
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.
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.
>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.
This is called churn and airlines are pretty on top of it. If you do this often then it will completely ruin your relationship with the airline. Maybe individual travel agencies can get away with it if they're trying to book a handful of tickets each week but OTAs can't.
> I think some airlines have changed their practice to avoid this.
AFAIK even direct connections still use the pattern of creating a PNR, confirming the booking, and then issuing a ticket. Even so in the US, airlines have to guarantee a full refund if a domestic flight is cancelled within 24 hours of booking.
