My main gripe with tipping is that it has just become so pervasive in recent years. Not only does everyone in just about every service industry expect a tip, that tip had better be no less than 20% or you'll hear complaining.
I have no problem leaving a good tip when it is customary, but that doesn't mean I can't question how much I feel that the services funded by my tipping are worth.
Your point is well taken. I had always thought 15% was the standard, but had taken to tipping 17-18-20% when I was happy and the dollar amount wasn’t too painful, but then someone “informed” me that the standard was now 20%, and I was like, by who’s authority? And as the other poster (maybe you) pointed out, tipping by percentage means that inflation covers itself. I think all the waitpeople better get used to 10% again or a lot of them are going to be out of work.