It’s unclear how long the practice has been going on—and unclear whether the rollback is permanent or temporary.
United and American all did not immediately respond to Fortune‘s request for comment. Delta declined to comment.
The study found the divergent fares weren’t universal. “You won’t see it on each and every route,” Thrifty Traveler wrote.
Dynamic pricing has long been a standard practice for airlines. Fares go up and down in real time, using historic booking data as a guide. Business travelers, who are the bread and butter of airline revenues, tend to travel solo, so one theory is that airlines are looking to increase their revenues from those travelers.
