I always thought this was just normal behaviour from everyone, everywhere. Like washing your hands after taking a shite lol. Hair-dressers/barbers an all. But then, through speaking to folk about it, I found out that while it's still more common than not there's plenty of people out there who think nothing at all of leaving no tip (to be fair, when in America I was often half tempted not to, because they fucking DEMAND it & sometimes actually kick off at people for not doing it, which makes me think "Fuck you, you're not getting it then!". That really annoys me actually. A tip is supposed to be something extra, not something included in the bill but not actually included in the bill, if that makes sense. "I need my tips to live!" well, fucking shout odds at your boss for more money, don't shout at me, the cunt who just forgot to leave a tip after already fucking paying you!!! You're obviously not getting it now ya wank" - that was pretty much a conversation I had in America, when I was fucking 16 & my mates mum was paying, hadn't left a tip & had left before us. Great fun walking out of a restaurant in Florida shouting abuse in thick Glaswegian lol.)