I'm not and never have been cabin crew. However, I used to work in a bar. For the first few months, the manager (later fired for stealing) was lazy and we all followed his lead. We'd sit around drinking and eating whatever we wanted for free. We served customers of course, but they felt like a distraction and we never rushed. We didn't usually bother clearing glasses as we found that eventually customers brought them back themselves. It was fun!
After he was fired the new manager ran a tight ship. We weren't allowed any alcohol, only soft drinks. If anyone offered to buy us a drink we would say we're not allowed and can they please tip in the jar instead if they wanted. We cleaned glasses, served customers with a smile and generally ran around keeping things clean and organised. For the first few days I missed lazing around and the free drinks! But then I realised I enjoyed the "proper" working environment more. I felt a sense of achievement, customers were happy, and it led to a small promotion (well, as far as a student can be promoted working in a pub!).
Why type all that self-indulgent stuff? What I'm saying is ... I'd expect all/most BA crew to do a great job if their leader motivates them by doing the same. So the fault lies with the CSD/CSM or whatever the manager is called.