Tipping... a question about tipping...?

Since when is a tip 20% anyway? Last I knew it was still 15% at most(glad I don't go out to eat). Anyway the thing is people that go to that more expensive restaurant plan to pay more and have more money. They may not have wanted drinks and all because they didn't have the budget for them. Just remember Tips were ORIGINALLY given BEFORE you were seated. It's To Insure Promptness. The more you gave the more the waiter would pay attention to you.