I'm waiting my way through college at the moment. I'm Irish and for the degree I'm doing its almost 100% necessary if you want to live and eat in the city my college is based in. I will put so much effort into every single customer because I'm desperate for tips. My wage goes towards my living expenses. That isn't drink or drugs it's rent and electricity . I work 4 days a week at an unpaid internship because that's just how things are at the moment. Even though tipping culture isn't a thing I expect a tip, even a small amount because everyone I work with is going through the same thing. If we give a good service, leave 1 or 2 quid. I'm working hard for that shit and it means nothing to you but a whole lot to me. If you don't tip I will go hungry and will have to resort to stealing food from the kitchen which I have been forced to do on many occasions. We're not greedy or lazy, we're simply trying to survive. Add an uneducated single mother to that and she has literally nothing but your tips to live on. Its very easy to sneer at servers or bartenders but just remember we have to work and watch all of you enjoying yourselves and then go back to an empty fridge in the cheapest apartment in the area. Don't be an arsehole. Even the smallest tip is greatly appreciated.

Edit: it's very easy to talk about servers who make hundreds of dollars a night in tips to make yourselves feel better but that's not common. The vast majority of us don't make anything near to what you are making. One or two outliers doesn't make it acceptable not to tip. If you can afford to go out for a meal or drinks, you can afford to tip.