She probably /was/ warned about her not emptying the cash registers - do you really think corporate knew about it because it wasn't in her records? They'd likely already given her chances to fix her failure to follow the policy, most businesses do because it's cheaper to write up an existing employee than to train a new one. However, they were robbed and it came out that she was again failing to follow the procedure. So basically she wasn't demoted before hand because they were giving her another chance, she blew it off and the shit they'd been warning her about happened.
Either way though they were stupid to think that this wouldn't harm their reputation, but maybe the manager at the franchise didn't think she'd bring it up to the media. That one manager is a bit of a ******* ass, no doubt. But the reality is that working, especially as a manager, is not as "fun" as you guys like to think. Regardless she's been offered her job back because corporate went "holy shit you idiot" and set the franchise straight on the PR disaster. I bet the manager who fired her has been given a serious talking to, if not been fired outright for his stupidity.
All well and good, media/social pressure has helped her get her job back plus a payoff. Problem is, she's likely to /not/ follow the company policy just as much as she hadn't before. I understand that you folks want to think that's no big deal, but policy is /not/ just about money for the company, the vast majority of these policies have a safety component. The end result is that she is /not/ management material but now the "outrage" has kept her in the position. That's not a good situation for ANYONE. But oh well.