As an AA EXP at the time, I had AA try to charge me to be rebooked into an alternate airport during IROPS. Was due to fly into JAX and arrive before noon but due to a mechanical delay out of CVG, I was going to misconnect in MIA and next flight with availability wasn't until late that night. I asked to be rerouted to TPA, where I would be driving to the next day. Agent told me I would incur a fare difference for that request. Meanwhile I've had DL change TPA to JAX for no fare difference just due a minor schedule change months in advance.