It is rather laughable to suggest that AA's IT is good. The systems in Australia work really well ; if someone has a flexible ticket then there is no issue at all going online and making the change or , at the airport, asking at the check in desk to get on to an earlier flight

If there is a reason that the airline wants to get people out earlier, then the checkin kiosks will inform the passenger checking in that he can get on an earlier flight if wishes to do so

If someone turns up at a check in desk and has an inflexible ticket, then will be generally just told that needs to wait for the next flight; there is not much in the way of agent roulette where may find an agent ignoring rules

As far as accepting baggage , that isn't an IT issue, that is the airports not wanting baggage for long periods of time - travel through nmerous countries in Asia , such as Singapore, Malaysia, UAE it is quite possible for bags to stay checked through for up to 24 hours on a connection with no issue , which is a lot better than what AA mamages in USA