There used to be a time that the norm was to tip the person doing the work if it was service related. Mechanics are a good example, computer techs, plumber, etc, etc, etc.
That's really become a thing of the past. Probably because the higher level of service that earned those tips has largely disappeared. I mean when was the last time you called a computer tech at 1am and had them show up 20 minutes later and only charge their regular rate with no absurd travel fees? And to actually do the job with a smile!
I don't tip nearly as often as I should. Sometimes I'll give the guy pumping my gas a few extra dollars as a tip, but beyond that I fail miserably.