Eastern European here. I remember going to Mallorca and see clubs advertise 20 EUR entry for an all-you-can-drink night. We went there just to see with our own eyes and indeed it was. Vodka + tonic or beer and not even cheap crappy one on tap in plastic cups but bottled beer in small bottles. No idea how it was profitable to them, we drank a lot but couldn't match the Brits there who got totally wasted :P