Originally Posted by
cova
I have never seen AA charge a passenger to move to the exit row or MCE.
On AA, payment for an MCE seat has to be done at the gate. The FA has no way to accept payment for the "upgrade". So it someone moves themselves after the door closes (and the GA is on the other side of that door), the FA's only option is to send them back to their original seat, even if the self-upgrader wants to pay for it. I've heard the FA tell them that they needed to handle with the GA, but once the door is closed, people need to sit in those seats according to the manifest.