I used to take same day round trip flights all the time. Isn’t it normal for business travel? I could leave home at 7am, fly to stinky Sydney, meet my customers, and be home again by 7pm.

> Airlines also do it to prevent people from "gaming" the system. People buy multi leg tickets and miss parts of the flights purposely in order to get higher airline status and points, or just to get to one city cheaper. Sometimes, they take roundtrip flights on the same day back and forth to gain points and airline flyer club status.

Late last year I flew aaa-bbb-aaa-bbb-ccc-ddd across Europe, all in one day, for exactly that reason. Five flights across four separate bookings/tickets. The connection at ccc was the tricky bit, not only "connecting" on a different ticket (so not really a connection), but a different airline alliance.

They design the system, you follow the rules. Unintended consequences aren't really your problem.

But they do pay for the return journey they didn't make, right? So where's the gain?