Most of the time the policy seems to be driven by "It's only property/money and we have insurance." Pretty much the same thing for pizza/Chinese/whatever delivery persons. Let the BG leave with whatever he wants because the customers next week will eventually make up the loss. And the few instances I have read about where the employee tries to sue the employer for being forced into defenselessness seem to be nothing but ways for attorneys to collect some fees on a case they know will be dismissed before the ink is fully dry on the complaint.
While one of the last things I want to see happen is for store employees to take on self-appointed police duties (loss prevention does a bad enough job at that) I really become distraught when a company fires employees who try to protect an innocent third party, let alone when they try to protect themselves. (And for those of you who would say the cop was dead when the employees tackled the [alleged - almost forgot to say that] shooter, please remember that they were not trained and certified to determine that he was in fact dead and therefore no longer in need of being defended.)