This is a good article, and it goes into detail in the origins of tipping and why different countries tip differently that I hadn't seen before. But it only covers the restaurant industry. What about all the other jobs where tipping is expected? How about jobs where we're unsure whether to tip?

For example, since this is Hacker News, how about all the service industry startups, such as the transportation companies Uber and Lyft, or Postmates, or Instacart, or the many others that have sprung up? Of all of these, Uber is the only one I can think of that explicitly doesn't provide a means to tip. Most of these companies do offer a way to tip (although they generally leave the default at $0). When I use one of these companies, occasionally I ask the driver / delivery person / whoever what the expectation is, and usually the answer is something along the lines of the tip is completely optional and is provided because some people explicitly want to tip. But this answer is very unsatisfying, since I don't know if they're being truthful or if they've been instructed to tell people it's optional. Ultimately, I'm always left with a little bit of anxiety about whether I really should be tipping, and if so, how much is appropriate.