These kinds of conversations are so interesting to me. It's such a toxic topic for most people to discuss. And if you pay careful attention, you'll notice that the entire tipping culture exists in that same kind of toxic funk—hostility brewing, perpetual judgment, and just general tension. The whole practice revolves around making people feel bad and instilling a sense of obligation. And of course it works fantastically well, if we consider the goal to be extracting money from consumers. But overall, it's just nasty and something I would like to see disappear.
Aside from a meaningless amount of time in Europe, my whole experience of tipping was in the U.S. Then I lived in Peru for a couple months last year, and several more months this year. What a difference!
Outside of the rare tourist trap, tipping is not generally a thing there. People do tip sometimes, you'll occasionally see a tip jar on a counter at a cafe or whatever, but there isn't this pervasive culture of burning into everyone's brains that you have to always tip a certain amount for certain services. It just doesn't exist.
You tip (a) if you want to, (b) if you feel the service warranted a tip, and (c) in an amount that works for you. There's no automatically adding a 20% surcharge to your bill or slipping an extra few bucks to cab drivers (who almost never get tipped). You leave a small-but-not-meaningless amount of money as a kind gesture.
And guess what? People actually appreciate it. Imagine that. They appreciate that you took it upon yourself to leave a small gift. Keep in mind, people are not making large amounts of money in these service professions. People make far less at these service jobs than they do in the U.S. (even relative to cost of living).
But still, they don't take a tip for granted. They don't treat it like just getting a paycheck that they're owed. They don't say things like, "If you can't afford to tip, you shouldn't have come out to eat," or "It doesn't matter how good the service is, you gotta tip at least 18%," or "Cheapskate customer only left me 14%." They don't sic their manager on you as you're leaving or post your receipt on Twitter if you didn't tip "enough."
There's no entitlement attitude. All of this bullshit toxicity simply doesn't exist. Tipping is a truly personal decision between you and the server, and no one else, and IMO that's what it should be.
next is my personal favorite - why should (insert lower wage profession) make $15(or whatever) and hour when EMT who save lives only make $18??? Why is the question not "Why don't EMTs make $30?". It's ridiculous. But I digress. 
