Multiculturalism is dead

[Tellos Athenaios]

That's not how it works in the USA though. In the USA you pay for the drink, you don't pay for the waiter. So leaving without a tip is equivalent to not paying the waiter, basically.
In the UK/Netherlands/Germany/France/Belgium it's more like you pay for both, but if the waiter/house are any good it is custom to leave a tip; tips are pooled and divided according to some scheme among staff. So a venue where both quality and service of the product is top notch sees a generous additional income for its staff meaning an incentive for all concerned to do their best and more business (profit) for the venue too.