There used to be a cracker of a flat roof pub on a notorious housing estate in Hanwell, West London about ten years agon. Selling beer was an inconvenience. It made far more from selling class A drugs.
We eventually managed to close it down (which was actually more difficult to do than it should have been). Unbelievably, the pubco appealed the closure. They lost the appeal and it was put up for sale. Nobody wanted to know and it was pulled down. One less to worry about.
Why would you want to go to one of those places when there are park benches and pigeons to shout at?
Much safer for the dealers to use anonymous cut outs, i.e. a kid on a bike with a PAYG mobile phone. The kid is hard to follow and legally they're pretty exempt from most police actions. Selling drugs in pubs would be needlessly risky these days.