Basically what Havelle said, waiters get paid below minimum wage most of the time and as a result if you don't tip you're basically ripping them off. Granted, no one can force you to tip so if the service really IS that bad, then no one will make you tip. I've personally never tipped anyone other than a waiter/bartender and my barber, and have only ever seen/heard of people tip the valet at a fancy restaurant, a delivery man who brought in a new couch and set it up for them, or people that fix stuff in the house, like a plumber/electrician (and for those guys it isn't so much like you give them a full 20% more or anything, but rather you slap an extra $5-10 in there an call it a day, which is usually peanuts compared to the overall bill). 99% of your tips will be at a restaurant, so I don't necessarily see how it is that out of hand (unless of course you've never tipped before and aren't used to it), with the other 1% being elsewhere in the service industry.
As for clapping, can confirm that people (sometimes) clap at the movies, which I always found to be the dumbest thing. Luckily that trend is kinda dying down around here, and it really only happens opening night/weekend for big blockbusters i.e. star wars or marvel movies that have a huge fan base. If the theater is far from filled up or you're seeing a more indy movie, almost no one bothers to clap. And yes, people clap when they arrive safely on an airplane, luckily I can't say if they clap otherwise.
