> Why did the tip percentage go up from 15% as the norm to like 18-20%

Why did it go up from 10% to 15% 50+ years ago? And why did it go up from 18-20% to 22-25% in the last few years?

> And why did it go up from 18-20% to 22-25% in the last few years?

Especially when they removed the separate server minimum wage at the same time, meaning that servers both moved up into the regular minimum wage and gained in tipping culture.