The idea it's a tradition to reward "good service" is exposed as specious simply by considering all the other service-based jobs where tips are not given. Do you tip your accountant, your lawyer, or your dentist ?
As has been said many times in this thread. There are places where tipping is expected and customary, but places where tipping is not expected and customary.
It's not a difficult concept. Try very hard to figure it out.