When I was a kid, 10% was fairly normal.
Last time I went to a restaurant in the US, I got scolded because I refused to tip when the waitress brought my food out cold and never once gave me a refill. I'm apparently "supposed" to tip 25% these days.
When people do their job, I'm okay with tipping. But I'm not OK with tipping based on the price of the meal. A person who works at a $70/plate restaurant and keeps filling my glass of water up with ice before I can finish it, making it unbearably cold, really isn't doing anything better than an overworked waiter in a $7/plate dirty hole in the wall shack. The skills don't differ (and I'm honestly often impressed with how skill-less waiters are at high-end American restaurants--they're worse than typical servers in any other country) and they're not the ones making the meals.
Just bring me a drink that's at least 90% drink and not 90% ice, bring my food out before it's cold, and get me a refill within a few minutes of running out and I have no trouble dropping $10 or $20--the price of the meal doesn't factor into that. Fail to do that, and you're getting nothing--I don't care how expensive the meal is that the chef prepared, but you had zero involvement so you're not entitled to that cash.
But I'm glad I'm not living in a place with a toxic restaurant culture, so it's not my problem anymore. :)