Many seem to be missing key points:
1. From clubs' perspective, many are run on the model of attracting and admitting as many as possible and serving as many shots and cheap drinks as quickly as possible to as many of them as possible as often as possible.
2. It's all very well talking about well-controlled pubs etc. but this risibly ignores the point that the masses who end up paralytic in the street every weekend early hours DO NOT WANT that type of environment, the clubs are providing them with what they want, which is a route to a long session into the early hours including getting totally off your face.
There is a good point about it being illegal to serve a drunk. If a customer comes out of X club off his or her face, then apart from anything else, it would be hard to defend a charge. But for some reason, I can't remember ever reading about a club being so charged. The police occasionally whinge about the state of people on the streets in the early hours, but whilst they are unlikely to modify the behaviour of the thousands whose lifestyle this is, why don't the clubs who have got people off their face ever get their collars felt?
I would imagine that one night of surveillance inside and outside one of those establishments would be enough to produce evidence of dozens if not hundreds of offences and this would be an effective solution as being summonsed for serving 100 drunks on one weekend would not endear you to the council alcohol licensing committee.
So my conclusion is that the police do not WANT to actually stop the paralytics being plied with drink until they are in that state.