Originally Posted by
BenA
The primary reason would be a business traveler who doesn't want to deal with expense report paperwork for their spouse's ticket when bringing them along.
With some companies/organizations it’s not possible to do that. I work for the DOD. There’s no way I can book a flight for my spouse if I book through our travel system, which I’m (usually) required to do.
Another completely valid reason is splitting payment options between tickets. For example, using Pay with Miles. If I want to use PWM miles or miles in general for one ticket and use full cash payment for another, I have to book separate tickets. If I use PWM on tickets booked together, it applies the requested PWM miles amount to both tickets. Other reasons might be booking from different tools. Say I book a DL with Skymiles for me and use Flying Blue miles to book a ticket for my spouse on the same flight. Again, not possible to book the flights on the same reservation in this case.