It happens, in the AA case, because of managements gross incompetence and dishonesty.
In this example management TOLD the gate agents to spread the late/oversleeping crew lie (#101 in their playbook) and it's not by any means an isolated case of them trying to deflect blame onto the employees for a management fark-up. As it happened, the crew arrived right when they were scheduled to via another flight..... unfortunately the company screwed that connection as the flight they were to crew was to leave just as they got to the airport. Management therefore fell back on trusty excuse #101.
Seems the employees of that airline are tired of apologizing for things totally out of their control and so they generally don't. Instead, many have taken to handing out cards with the CEOs phone number on it. "Don't waste your anger on me because I'm pissed off as well. Call him."