re: Has 20% become the new standard for tipping?

If you're too cheap to tip 20% then you're probably too cheap to be going out to eat. Unless the service sucks I'm always tipping at minimum 20%.

The difference between leaving 15% and 20% generally means a difference of $6 or less, and to the people serving you that 15% to 20% difference usually means a whole helluva lot more to them than the extra $1-$6 dollars to you.

That's their job, livelihood, way they get by for school, whatever it is their reason they are working for tips. And don't fault them because you disagree with the American tip system. It's not their fault so don't be a cheap arse, it's probably less than $6 anyways.