Regarding tipping in pubs in the UK: Ah, but eventually you have to (at least offer to) buy the barman (or woman) a drink, so it comes out to the same thing, no?
When I lived in Europe, I followed European tipping customs, and when I visit Europe now, I do the same. When I'm in the U.S., I follow American tipping customs. If I were to walk about the U.K. proclaiming the the inadequacies of the British system loudly and at length--or do the same on a U.K.-based Web site--you'd call me an ugly American, wouldn't you?
And you'd be right.