Originally Posted by
guv1976
What difference does the "why" make? And did you try to pay for the baggage at a check-in kiosk at the airport?
Exactly. It sounds like the OP is used to LCCs. But with AA or any of the legacy airlines, paying online vs paying at the kiosk at the airport isn't going to save you any time or money. There is no "penalty" for paying at the airport like the LCCs have.