They do it on purpose. The less patrons talk to each other the more alcohol they drink. That's why the music volume is increased as the night progresses. They get them into the establishment, customers start drinking, eventually it gets to a point where they can't hear each other so they just focus on drinking. Not all places do this, just the places that are strongly focused on the profits.
sukilot|11 years ago
If bars wanted to sell more drinks, they would have more bartenders to reduce the wait times.
superme|11 years ago
It mainly happens in busy city bars/pubs, where repeat customers aren't so important.