Nothing wrong with also having a charity collection box on the bar, but expecting all staff to hand over all tips for a month, to a charity they may or may not personally wish to support? That’s utterly wank behaviour.
Exactly. Doesn't matter which charity they donate to, forcing low paid workers to donate their income is morally wrong. Plenty of ways for a business to fund raise or donate that don't involve docking staff wages.
(So, in the circumstances really not surprising that they haven't checked out the charity)