This is very true. also, what I think is bad, as I seen it, as I owned a bar. Someone would pick up some one else's tab. So that person assumes the person picking up the tab, will also take care of the tip. Even if they do, that person still should tip the bartender / wait staff. Especially if the person paying the tab doesn't give the extra tip, only for their own. But almost all the time, they don't.