I drink coffee with a touch of cream.
I mentioned doctors and lawyers to preempt the common counter-argument that the tipping tradition is necessary to assure good service.
I would do away entirely with the tipping tradition. Let business owners pay their employees what they are worth instead of expecting their customers to do it for them.
Tipping is an obnoxious, extortive practice that allows business owners to dishonestly post deceptively low prices.